JP2020040765A - Sheet feeding apparatus and image forming apparatus - Google Patents

Abstract

To further increase a sheet conveying force in a sheet feeding apparatus capable of changing an angle of a manual feeding tray.SOLUTION: The sheet feeding apparatus includes: a manual feeding tray on which sheets are loaded; feeding means for feeding sheets loaded on the manual feeding tray; a pull-out conveyance roller for conveying a sheet fed by the feeding means; a driven roller for pressing against the pull-out conveyance roller; and pressurizing means for pressing the driven roller against the pull-out conveyance roller. The manual feeding tray can be opened to a first feeding position opened in a direction away from an apparatus body and to a second feeding position opened further from the first feeding position in a direction away from the apparatus body. The pressurizing means changes a pressing force of the driven roller against the pull-out conveyance roller between a case where the manual feeding tray is located at the first feeding position and a case where the manual feeding tray is located at the second feeding position.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sheet feeding device that feeds a sheet.

  Usually, the image forming apparatus is provided with a manual paper feed unit. The manual sheet feeding unit stacks sheets on a manual tray, separates the sheets one by one by a sheet feeding unit, and supplies the sheets to the image forming unit. The manual feed unit has a manual feed tray that is rotatably supported on a side surface of the image forming apparatus main body, and is used with the manual feed tray opened.

  By the way, users in the market are required to support a wide range of paper types and basis weights, and in particular, demands for thick paper, envelopes, and long papers are increasing. In order to respond to this demand, in recent years, an apparatus has been proposed which can adjust the angle of the manual feed tray to a direction in which the manual tray is laid down more than the normal tray angle during transport. Japanese Patent Application Laid-Open No. H11-163873 discloses a feeding method that changes the angle of a stacking portion on which a sheet is stacked so that the sheet is conveyed in a more linear conveyance path, reduces the conveyance load due to the type of sheet, and improves the media conveyance performance. A transmission device is disclosed.

JP-A-10-59554

  The manual feeding device described in Patent Literature 1 aims at improving transportability by reducing the transport load. However, the demand for a wide range of paper types and basis weights from market users is increasing year by year.Therefore, there are many media that cannot be handled simply by reducing the transport load in order to handle more thick paper, envelopes, and long paper. are doing.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a sheet feeding apparatus capable of further improving a sheet conveying force.

  In order to achieve the above object, a sheet feeding device according to the present invention includes an apparatus main body, a manual tray supported to be openable and closable with respect to the apparatus main body, and a manual tray on which sheets are stacked, and a sheet loaded on the manual tray. A pickup roller for feeding the sheet, a feed roller for conveying the sheet fed by the pickup roller, and a separation nip formed by pressing against the feed roller to separate two or more sheets by the pickup roller A retard roller that separates one sheet from the two or more sheets when fed to the nip; a pull-out transport roller that transports the sheet transported from the feed roller downstream; A driven roller that presses the driven roller, and pressurizing means that presses the driven roller against the pull-out transport roller; Can be opened to a first feeding position opened in a direction away from the apparatus main body, and a second feeding position opened further in a direction away from the apparatus main body from the first feeding position. It is possible that the pressurizing unit is configured to move the manual feed tray to the pull-out transport roller of the driven roller when the manual feed tray is located at the first feed position and when the manual feed tray is located at the second feed position. Is characterized by changing the pressing force of.

  According to the present invention, it is possible to reduce the occurrence of paper feeding failure by optimizing the pressing force on the pull-out conveyance roller in conjunction with the change in the position of the manual feed tray with respect to the apparatus main body.

Diagram showing a schematic configuration of an image forming apparatus Sectional view showing a sheet feeding device according to the first embodiment. Sectional view showing a sheet feeding device according to a second embodiment.

〔overall structure〕
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. Is not intended to be limited to the following embodiment.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a full-color laser beam printer as an example of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the image forming apparatus 201 includes a main body 201A and an image forming unit 201B that forms an image on a sheet. Further, the image forming apparatus 201 has an image reading device 202 installed substantially horizontally above the main body 201A, and a discharge space B for discharging a sheet is formed between the image reading device 202 and the main body 201A.

  The image forming apparatus 201 includes a sheet cassette 1 that is a sheet storage unit that stores sheets S, and a feeding unit 230 that feeds the sheets S from the sheet cassette 1. The feeding unit 230 includes the pickup roller 8, a feed roller 9 for separating the sheet S sent from the pickup roller 8, and a retard roller 10.

  Further, the image forming apparatus 201 has a manual feed unit 500 having a manual tray 560 (stacking unit) on which sheets S are stacked, which is supported by the apparatus main body 201A so as to be openable and closable. The sheet S is fed to the image forming unit 201B. Details of the manual feeding section 500 will be described later with reference to FIG.

  The image forming unit 201B, which is an image forming unit, is of a four-drum full-color type, and includes a laser scanner 210 and toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K). Are provided. Here, each process cartridge 211 includes a photosensitive drum 212, a charger 213 as charging means, and a developing device 214 as developing means. The image forming unit 201B includes an intermediate transfer unit 201C disposed above the process cartridge 211 and a fixing unit 220. A toner cartridge 215 supplies toner to the developing device 214.

  The intermediate transfer unit 201C includes an intermediate transfer belt 216 wound around a drive roller 216a and a tension roller 216b. In addition, a primary transfer roller 219 that contacts the intermediate transfer belt 216 at a position facing the photosensitive drum 212 is provided inside the intermediate transfer belt 216. Here, the intermediate transfer belt 216 is rotated in a direction indicated by an arrow by a driving roller 216a driven by a driving unit (not shown).

  Then, the primary transfer roller 219 transfers the respective color toner images having the negative polarity on the photosensitive drum to the intermediate transfer belt 216. A secondary transfer roller 217 for transferring the color image formed on the intermediate transfer belt to the sheet P is provided at a position facing the drive roller 216a of the intermediate transfer unit 201C. Further, a fixing unit 220 is disposed above the secondary transfer roller 217, and a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing unit 201D are disposed at the upper left of the fixing unit 220. . The double-sided reversing unit 201D is provided with a pair of reversing rollers 222 capable of normal and reverse rotation and a re-conveying path R for re-conveying the sheet S on which an image is formed on one surface to the image forming unit 201B. In FIG. 1, reference numeral 260 denotes a control unit (control unit) that controls an image forming operation, a sheet feeding operation, and the like.

  Next, an image forming operation of the image forming apparatus 201 will be described. First, when image information of a document is read by the image reading device 202, the image information is subjected to image processing, converted into an electric signal, and transmitted to the laser scanner 210 of the image forming unit 201B. In the image forming unit 201B, the surface of the photosensitive drum 212 whose surface is uniformly charged to a predetermined polarity and potential by the charger 213 is sequentially exposed by the laser beam. Thus, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum of each process cartridge 211.

  Thereafter, the electrostatic latent image is developed with each color toner to be visualized, and each color toner image on each photosensitive drum is sequentially superimposed on the intermediate transfer belt 216 by the primary transfer bias applied to the primary transfer roller 219. Transfer together. As a result, a toner image is formed on the intermediate transfer belt 216. Further, the sheet S is fed from the pickup roller 8 provided in the feeding unit 230 in parallel with the toner image forming operation. The fed sheet S is separated one by one by a separation unit including the feed roller 9 and the retard roller 10 and is conveyed to the registration roller pair 240. The skew is corrected by the registration roller pair 240.

  After the skew is corrected, the sheet S is transported to the secondary transfer unit by the registration roller pair 240, and the toner image is formed on the sheet S by the secondary transfer bias applied to the secondary transfer roller 217 in the secondary transfer unit. The images are collectively transferred onto S. Next, the sheet S to which the toner image has been transferred is conveyed to the fixing unit 220, where the toner of each color is melted and mixed by receiving heat and pressure in the fixing unit 220, and is fixed on the sheet S as a color image.

  Thereafter, the sheet S on which the image is fixed is discharged to the discharge space B by the first discharge roller pair 225a and the second discharge roller pair 225b provided downstream of the fixing unit 220, and is projected to the bottom surface of the discharge space B. Are stacked on the stacking section 223. When an image is formed on both sides of the sheet S, after the image is fixed, the sheet S is conveyed to the re-conveying path R by the pair of reversing rollers 222, and conveyed again to the image forming unit 201B.

[Manual feed section]
The manual feeder 500 will be described in detail with reference to FIG. As shown in FIG. 2, the manual feed unit 500 includes a separation frame 570 (apparatus main body), a manual tray 560 that is supported by the separation frame 570 so as to be openable and closable about a rotation shaft 561, and on which sheets S are stacked. ,have.

  When the sheet S is fed from the manual feed unit 500, the user uses the sheet with the manual tray 560 opened.

  In this embodiment, the manual feed tray 560 can take a first feeding position shown in FIG. 2A and a second feeding position shown in FIG. 2B. The first feeding position is a position opened in a direction away from the apparatus main body 201A and positioned by a stopper (not shown). The second feeding position is a position that is opened in a direction in which the manual feed tray 560 is laid down more than the first feeding position and is positioned by a stopper (not shown). As described above, the manual feed tray 560 of the present embodiment can be set at two angles between the first feeding position and the second feeding position.

  Then, when an image forming job is input, the pickup roller 510 descends and comes into pressure contact with the upper surface of the sheet S. The pickup roller 510 feeds the sheets S stacked on the upper surface of the manual feed tray 560 toward the separation nip portion Nb. To the retard roller 530, a drive in a direction opposite to the sheet conveying direction is input by a motor (drive source) via a torque limiter (not shown). The torque value of the torque limiter is set to be larger than the frictional force generated between the sheets S due to the coefficient of friction of the sheets S, while set to be smaller than the frictional force generated by the coefficient of friction between the sheet S and the retard roller 530. I have.

  Accordingly, when one sheet enters the separation nip portion Nb or when no sheet enters, the retard roller 530 follows the feed roller 520. On the other hand, when there are two or more sheets entering the separation nip portion Nb, the retard roller 530 reverses with respect to the transport direction and separates the sheets one by one.

[Effect of transport resistance]
Incidentally, sheets used as recording media for the image forming apparatus 201 have various sizes and types. For example, examples of the sheet type include plain paper, special paper such as cardboard and coated paper, sheets having a special shape such as envelopes and index paper, and plastic films and cloths for overhead projectors. It is known that the magnitude of the conveyance resistance acting on the sheet in the direction opposite to the conveyance direction when conveying the sheet differs according to the size and type of the sheet. One of the main factors of the conveyance resistance is the friction between the guide member forming the conveyance path and the sheet. Therefore, the higher the rigidity of the sheet is, the more severe the curvature of the conveyance path is (the smaller the radius of curvature). As the transfer resistance increases, the transport resistance tends to increase. Examples of the sheet having high rigidity include cardboard, coated paper, and an envelope.

  In the case of the present embodiment, as shown in FIGS. 2A and 2B, a conveyance path formed by the conveyance guide 61 and guiding the fed sheet is in a width direction orthogonal to the sheet feeding direction. And includes a curved portion 61a that is curved when viewed from above. The curved portion 61a is located between the pull-out conveyance roller 580 and the registration roller pair 240 in the sheet feeding direction. The sheet S set on the manual feed tray 560 provided on the side of the printer main body 201A is fed in a substantially horizontal direction and fed into the inside of the printer main body 201A, and then guided upward along the curved portion 61a. Then, it reaches the registration roller pair 240. Therefore, the sheet that is passing through the curved portion 61a of the transport guide 61 is curved along the curved portion 61a, and is likely to receive greater transport resistance than other portions.

  If the conveyance resistance is large, the pull-out conveyance roller 580 slips with respect to the sheet, and there is a possibility that an abnormality such as conveyance delay or sheet jam is generated. Therefore, in order to improve the sheet conveyance force, it is important to improve the conveyance force of the pull-out conveyance roller 580 located on the upstream side in the conveyance direction of the curved portion 61a. Generally, by increasing the nip pressure on the pull-out conveyance roller 580, the conveyance force of the conveyance roller can be increased.

[Bypass tray angle]
As the bending of the curved portion 61a of the transport guide 61 becomes steeper (the radius of curvature is smaller), the transport resistance changes depending on the angle of the manual feed tray 560 as well as the transport resistance increases. In the second feeding position (FIG. 2B) where the angle of the manual feed tray 560 is further lowered as compared with the first feeding position (FIG. 2A), the curvature of the sheet S can be made gentler. It becomes possible. In particular, the effect is remarkable for long paper that is long in the transport direction. Therefore, in order to improve the conveyance resistance of the thick paper, the coated paper, the envelope, and the long paper, it is important to reduce the conveyance resistance, and it is effective to change the angle of the manual feed tray 560 to a more laid-down side. is there.

  Therefore, the manual feed unit 500 of the present embodiment includes a pressing unit having a holder 540 that swingably supports a driven roller 590 that is a driven rotating body, and an urging spring 550. The holder 540, which is an example of a support member, is a crank arm that is supported by the separation frame 570 so as to be rotatable around a rotation shaft 541, and is bent at a substantially right angle with the rotation shaft 541 therebetween.

  A driven roller 590 is rotatably supported at one end of the holder 540, and an urging spring 550, which is an example of an urging member, is supported at the other end 542. Further, the manual feed tray 560 has a contact portion 562 at an end near the retard roller 530 to be in contact with one end of the biasing spring 550, and the biasing spring 550 contacts the other end 542 of the holder 540. It is sandwiched between the contact portion 562. The pull-out transport roller 580 forms a pull-out transport nip Nh with the driven roller 590.

[Operation of pressurizing means]
With the above-described configuration, when the manual feed tray 560 is located at the first feeding position, the urging spring 550 has the urging force B1 as shown in FIG. The urging force B1 is transmitted via the holder 540. As a result, the driven roller 590 comes into pressure contact with the pull-out conveyance roller 580 at a predetermined nip pressure (pressure).

  The angle at the first feeding position of the manual feed tray 560 is a regular use angle, and the nip pressure (pressing force) of the pull-out nip portion Nh is set so that the angle can secure sufficient feeding performance for a general paper type. Is set.

  When the manual tray 560 is rotated from the first feeding position to the second feeding position, the contact portion 562 approaches the other end 542 of the holder 540 as shown in FIG. For this reason, the biasing spring 550 has a biasing force B2 greater than the biasing force B1 (B2> B1). In the state shown in FIG. 2B, the nip pressure (pressing force) at the pull-out conveyance nip portion Nh is lower than the state where the manual feed tray 560 is located at the first feeding position (the state shown in FIG. 2A). The sheet conveyance force increases.

  Conversely, when the manual feed tray 560 is rotated from the second feeding position to the first feeding position, the urging force of the urging spring 550 becomes relatively small, and the nip pressure at the pull-out conveyance nip portion Nh is reduced. Decrease relatively.

  That is, the pressing force of the driven roller 590 on the driven roller 590 by the pressurizing unit can be changed according to the position (the first feeding position, the second feeding position) of the manual feed tray 560.

[When transporting thick paper, coated paper, envelopes and long paper]
When conveying thick paper, coated paper, envelopes and long paper from the manual feed tray 560, the manual feed tray 560 is rotated from the first feeding position to the second feeding position. This makes it possible to simultaneously reduce the transport resistance due to the change in the angle of the manual feed tray 560 and improve the transport force due to the increase in the nip pressure in the pull-out transport nip Nh. Therefore, even a sheet having higher rigidity can be conveyed, and occurrence of conveyance failure can be reduced without limit.

  In addition, since the nip pressure of the pull-out conveyance nip portion is mechanically changed in accordance with the feeding position of the manual feed tray 560, a simple operation of merely changing the position of the manual feeding tray 560 by the user can prevent the feeding failure. The occurrence can be prevented as much as possible. Further, no additional actuator or the like is required as compared with the conventional configuration, so that no cost increase occurs.

(Second embodiment)
Next, the configuration of a manual sheet feeding unit that is a sheet feeding device according to the second exemplary embodiment will be described. The manual feed unit 500 according to the present embodiment is different from the first embodiment in that a long tray 563 for long paper is attached to a manual tray 560, and other configurations are the same as those of the first embodiment. This is common with the embodiment. Therefore, components common to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIGS. 3A and 3B, when the long paper is transported, the influence of the curvature of the entire long paper including the curved portion 61 a of the transport guide 61 and the manual feed tray 560 is more remarkable. Becomes

  In the second feeding position (FIG. 3B) in which the angle of the manual feed tray 560 is further lowered as compared with the first feeding position (FIG. 3A), the curvature of the sheet S can be made gentler. Becomes

  Therefore, in order to improve the conveyance resistance of the long paper, it is important to reduce the conveyance resistance, and it is more important to change the angle of the manual feed tray 560 to the side where it can be laid down.

240 registration roller pair (second conveying means)
500 Manual sheet feeding unit 510 Pickup roller (feeding means)
520 Feed roller (transportation means)
530 retard roller (separation means)
540 Holder 550 Urging spring 560 Manual feed tray 570 Separation frame 580 Pull-out conveyance means 590 Follower roller 610 Transport guide

Claims (6)

The device body,
A manual tray on which sheets are stacked and supported so as to be openable and closable with respect to the apparatus main body,
A pickup roller for feeding sheets stacked on the manual feed tray,
A feed roller for conveying the sheet fed by the pickup roller,
A retard roller that forms a separation nip by pressing against the feed roller, and separates one sheet from the two or more sheets when two or more sheets are fed to the separation nip by the pickup roller. When,
A pull-out conveyance roller for conveying the sheet conveyed from the feed roller downstream,
A driven roller pressed against the pull-out transport roller,
Pressurizing means for pressing the driven roller against the pull-out transport roller,
With
The manual feed tray is located at a first feeding position opened in a direction away from the apparatus main body, and a second feeding position opened further in a direction away from the apparatus main body from the first feeding position. Can be opened,
The pressurizing unit is configured to reduce a pressing force of the driven roller to the pull-out conveyance roller when the manual feed tray is located at the first feeding position and when the manual feeding tray is located at the second feeding position. A sheet feeding device characterized by changing.   The pressing force of the driven roller on the pull-out conveyance roller is larger when the position of the manual feed tray is located at the second feeding position than when it is located at the first feeding position. The sheet feeding device according to claim 1, wherein   The device according to claim 1, wherein the pressing unit includes a support member that swingably supports the driven roller, and a spring provided between the support member and the manual feed tray. 4. Sheet feeding device. The support member rotatably supports the driven roller at one end, and is a crank arm rotatably supported by the apparatus body,
The sheet feeding device according to claim 3, wherein the spring is provided between the other end of the crank arm and the manual feed tray. A second conveyance roller disposed downstream of the pull-out conveyance roller in a sheet feeding direction;
The sheet feeding device according to claim 1, wherein a conveyance path between the pull-out conveyance roller and the second conveyance roller is curved. A sheet feeding device according to any one of claims 1 to 5,
An image forming unit that forms an image on a sheet fed by the sheet feeding device;
An image forming apparatus comprising:

Images