JP2017088299A - Sheet feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeding device and an image forming apparatus which can reduce the occurrence of feeding failure regardless of the position of loading means.SOLUTION: A sheet feeding device includes: a manual feeding tray 560 (loading means) which is loaded with sheets; a pickup roller 510 (feeding means) which feeds the sheets loaded in the manual feeding tray 560; a feed roller 520 (conveyance means) which conveys the sheets fed by the pickup roller 510; a retarded roller 530 (separation means) which forms a separation nip part N by being brought into pressure-contact with the feed roller 520, and separates the sheets fed by the pickup roller 510 one by one in the separation nip part N; and a pressing unit 590 (pressing means) which presses the retarded roller 530 to the feed roller 520. The pressing unit 590 continuously changes the pressing force of the retarded roller 530 to the feed roller 520 in accordance with the position of the manual feeding tray 560 with respect to a separation frame 570 (device body).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sheet feeding apparatus that feeds a sheet and an image forming apparatus including the sheet feeding apparatus.

  In general, an image forming apparatus such as a printer is provided with a manual feeding device that can feed sheets of various sizes. This manual feed device has a manual feed tray rotatably supported on the side surface of an image forming apparatus main body (hereinafter referred to as “apparatus main body”), and is used with this manual feed tray open.

  Conventionally, there has been proposed a manual feeding device including a pickup roller for feeding sheets stacked on a manual feed tray, and a feed roller and a retard roller for separating the sheets fed by the pickup roller one by one. (See Patent Document 1). The retard roller of this manual feeding device receives a driving force in a direction opposite to the sheet feeding direction via a torque limiter, and is pressed against the feed roller by a spring or the like. The manual feeding device realizes sufficient sheet separation performance by appropriately setting the torque value of the torque limiter and the pressure contact force (nip pressure) of the retard roller to the feed roller.

JP 2014-125333 A

  By the way, the manual feed device described in Patent Document 1 is normally used with the manual feed tray fully opened. However, depending on the actual use environment of the user, a sufficient ground space for the image forming apparatus should be ensured. May be difficult. In this case, the manual feeding device may be used in a state where the manual feed tray is opened halfway without being fully opened.

  When the angle of the manual feed tray changes, the sheet's own weight and the angle of entry of the sheet into the separation nip formed by the feed roller and the retard roller change. As a result, the optimum pressure contact force of the retard roller and the torque limiter torque value set with the manual feed tray fully open do not become the optimum paper feed conditions, and there is a risk of poor feeding such as double feeding. There is.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet feeding apparatus and an image forming apparatus that can reduce the occurrence of feeding failure regardless of the position of a stacking unit (manual feed tray).

  The present invention relates to a sheet feeding apparatus, an apparatus main body, a stacking unit that is movably supported with respect to the apparatus main body, and stacks sheets, and a feeding unit that feeds the sheets stacked on the stacking unit A conveying unit that conveys the sheet fed by the feeding unit; and a separation nip portion that is pressed against the conveying unit to form a separation nip portion. The sheet fed by the feeding unit is A separating unit that separates the sheets one by one; and a pressing unit that pressurizes the separating unit against the conveying unit. The pressurizing unit is configured to move the separating unit according to a position of the stacking unit with respect to the apparatus body. The pressure applied to the conveying means is continuously changed.

  According to the present invention, depending on the position of the loading means relative to the apparatus body, the pressure applied to the conveying means of the separating means changes continuously, so even if the loading means is used in a halfway position, Occurrence of poor feeding can be reduced.

1 is an overall schematic diagram illustrating a printer according to an embodiment. 4A and 4B are side views showing a manual feed unit, in which FIG. 5A shows a state where the manual feed tray is positioned at the open position, and FIG. 5B shows a state where the manual feed tray rises from the open position by a predetermined angle. It is a side view which shows the manual feed part which concerns on a comparative example, Comprising: (a) is the state in which a manual feed tray is located in an open position, (b) is the state which stood up the predetermined angle from the open position.

〔overall structure〕
A printer 100 (image forming apparatus) according to an embodiment of the present invention is an electrophotographic laser beam printer. As shown in FIG. 1, the printer 100 includes an image reading device 200 that reads an image of a document G stacked on a document tray 221, and an image forming apparatus main body (hereinafter referred to as a printer main body) 10.

  The image reading apparatus 200 includes a scanner unit 210 that reads an image of a document G, and an automatic document feeder (hereinafter referred to as ADF) 220 that automatically feeds the document G to the scanner unit 210. The image reading apparatus 200 reads an image on the first side of the original G by the first reading unit 211 provided in the scanner unit 210, and an image on the second side of the original G by the second reading unit 251 provided in the ADF 220. Can be read.

  The printer body 10 includes a sheet feeding unit 30 that feeds stacked sheets, an image forming unit 20 (image forming unit) that forms an image on the sheet, a fixing unit 25 that fixes a toner image on the sheet, and a manual feed A feeding unit 500 (sheet feeding device) and a control unit 50 are provided.

  When an image formation command is output to the printer 100, an image forming process by the image forming unit 20 is started based on image information input from the image reading apparatus 200 or an external computer connected to the printer 100 or the like. . The following image forming process and sheet feeding process are controlled by the control unit 50. The image forming unit 20 includes a photosensitive drum 22, a laser scanner unit 21 that irradiates the photosensitive drum 22 with laser light, a charging member 26, a developing device 23, and a transfer unit 24.

  The laser scanner unit 21 irradiates the photosensitive drum 22 with laser light based on the input image information. At this time, the photosensitive drum 22 is charged in advance by the charging member 26, and an electrostatic latent image is formed on the photosensitive drum 22 by being irradiated with laser light. Thereafter, the electrostatic latent image is developed by the developing unit 23 and a toner image is formed on the photosensitive drum 22.

  In parallel with the above-described image forming process, the sheet S is fed from the sheet feeding unit 30 or the manual feeding unit 500. For example, when a sheet is fed from the sheet feeding unit 30, the pickup roller 32 feeds the sheets S stacked on a plurality of sheet cassettes 31 formed so as to be able to be pulled out from the printer main body 10. The sheets S fed by the pickup roller 32 are separated one by one by the feed roller 33 and the separation roller 34 and conveyed to the registration roller pair 11.

  The skew image is corrected by the registration roller pair 11, and the toner image on the photosensitive drum 22 is transferred by the transfer unit 24 to the sheet S conveyed at a predetermined conveyance timing. The sheet S to which the toner image has been transferred is given predetermined heat and pressure at the fixing unit 25, and the toner is melted and fixed. The sheet S that has passed through the fixing unit 25 is discharged to the discharge tray 45 by the discharge roller pair 46. When images are formed on both sides of the sheet, the sheet S that has passed through the fixing unit 25 is conveyed to the reversal conveyance path 12 in a state where the front and back of the sheet and the front and back are reversed. Then, the sheet S is conveyed again to the registration roller pair 11, and the toner image is transferred by the transfer unit 24.

[Manual feeding section]
Next, the manual feed unit 500 will be described in detail. As shown in FIG. 2, the manual feed unit 500 is supported by a separation frame 570 (device body) fixed to the printer main body 10, and can be opened and closed (movable) around the rotation shaft 561 by the separation frame 570. , And a manual feed tray 560 on which the sheets S are stacked. The manual feeding unit 500 includes a pickup roller 510 (feeding unit), a feed roller 520 (conveying unit), and a retard roller 530 (separating unit) that presses against the feed roller 520 to form a separation nip N. ,have. The manual feed tray 560 is closed to the printer main body 10 so as to be substantially flush with the side surface of the printer main body 10, and an open position (for example, FIG. 2 (a)).

  When the sheet S is fed from the manual feed unit 500, the user uses the manual feed tray 560 in an opened state. When the sheet feeding job is output, 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 N.

  The retard roller 530 receives a drive in a direction opposite to the sheet conveying direction by a motor M (drive source) via a torque limiter 580. The torque value of the torque limiter 580 is set to be larger than the friction force generated between the sheets S due to the friction coefficient of the sheet S, while being smaller than the friction force generated due to the friction coefficient between the sheet S and the retard roller 530. ing. As a result, when one sheet enters the separation nip portion N or when no sheet enters, the retard roller 530 rotates with the feed roller 520. On the other hand, when two or more sheets enter the separation nip portion N, the retard roller 530 reverses in the conveyance direction and separates the sheets one by one.

  Next, the main part of the present invention will be described. The manual feeding unit 500 includes a pressurizing unit 590 (pressurizing means) having a retard roller holder 540 that supports the retard roller 530 in a swingable (movable) manner, and a retard spring 550. The retard roller holder 540 (support member) is a crank arm that is supported by the separation frame 570 so as to be rotatable about a rotation center 541 and is bent at a substantially right angle with the rotation center 541 therebetween.

  A retard roller 530 is rotatably supported at one end of the retard roller holder 540, and a retard spring 550 (biasing member) is supported at the other end 542. Further, the manual feed tray 560 has a locking portion 562 that locks one end of the retard spring 550 at the end close to the retard roller 530, and the retard spring 550 is engaged with the other end 542 of the retard roller holder 540. It is stretched between the stop portion 562.

[Pressure unit action]
With the above configuration, when the manual feed tray 560 is located at the open position, for example, as shown in FIG. 2A, the retard spring 550 has a tension B1, and the retard roller 530 has a tension B1. Via 540. Thereby, the retard roller 530 is pressed against the feed roller 520 with a predetermined nip pressure.

  When the manual feed tray 560 approaches the closed position from the open position, the locking portion 562 approaches the other end 542 of the retard roller holder 540 as shown in FIG. For this reason, the retard spring 550 has a tension B2 smaller than the tension B1 (B2 <B1). In the state shown in FIG. 2B, the nip pressure in the separation nip portion N is smaller than that in the state where the manual feed tray 560 is located at the open position (the state shown in FIG. 2A).

  Conversely, when the manual feed tray 560 is brought close to the open position from the closed position, the tension of the retard spring 550 increases and the nip pressure at the separation nip portion N increases. That is, the pressure applied to the feed roller 520 by the retard roller 530 continuously changes according to the position of the manual feed tray 560.

  Here, the collision input to the separation nip portion N due to the weight of the sheet according to the open / close position of the manual feed tray 560 will be described. When the manual feed tray 560 is located at the open position, as shown in FIG. 2A, the collision input due to the weight of the sheet S is set to the collision input F1. When the manual feed tray 560 approaches the closed position from the open position, as shown in FIG. 2 (b), the manual feed tray 560 rises, so that the collision input due to the weight of the sheet S is larger than the collision input F1. (F2> F1).

  In the manual feed tray 560, the nip pressure and torque value of the separation nip portion N are set so that the angle at the open position becomes the normal use angle due to the sheet setting property and the like, and sufficient feeding performance can be secured at this angle. When the torque value of the torque limiter 580 is constant, the sheet is likely to be double fed when the collision input increases. In this case, by reducing the friction force between the sheets S, the double feeding of the sheets can be reduced, but the friction force between the sheets S is proportional to the pressure contact force (nip pressure) of the separation nip portion N. In the present embodiment, the change of the position of the manual feed tray 560 increases or decreases the collision input (F1 or F2) of the sheet S to the separation nip portion N. However, the pressure unit 590 performs separation so as to cancel it out. The nip pressure at the nip portion N increases or decreases.

  More specifically, as shown in FIG. 2A, the nip pressure is determined when the manual feed tray 560 is located at the open position and the sheet S is pressed against the separation nip portion N by the collision input F1. The retard spring 550 has a tension B1. As shown in FIG. 2B, when the manual feed tray 560 approaches the closed position from the open position, the sheet S comes into pressure contact with the separation nip portion N with the projection input F2 larger than the projection input F1, and the retard spring 550 is applied with the tension B1. Has a small tension B2.

  For this reason, for example, even if the manual feed tray 560 is held at a halfway angle between the open position and the closed position because the installation space of the printer 100 cannot be sufficiently secured, Such as poor feeding can be reduced.

  In addition, since the nip pressure of the separation nip portion automatically changes mechanically, it is possible to prevent the occurrence of feeding failure as much as possible without causing troublesome operations for the user. Further, since the number of parts and the addition of sensors, actuators, etc. are not required compared to the conventional configuration, the cost does not increase.

<Comparative example>
Next, a manual feeding unit 600 as a comparative example will be described. This comparative example differs from the embodiment of the present invention only in that the retard spring 550A is connected to the separation frame 570 instead of the manual feed tray 560. For this reason, about the structure similar to this Embodiment, the same code | symbol is attached | subjected to a figure and description is abbreviate | omitted.

  The retard spring 550 </ b> A of the manual feed unit 600 is stretched between the other end 542 of the retard roller holder 540 and the separation frame 570. For this reason, the nip pressure of the separation nip portion N is constant regardless of the opening / closing angle of the manual feed tray 560. Then, as shown in FIG. 3B, in the state where the manual feed tray 560 is raised by a predetermined angle from the open position, there is no configuration that cancels out the increase in the collision input due to the weight of the sheet S, so that the sheet double feed occurs. It becomes easy to do.

  In the present embodiment, the retard roller holder is configured by a crank arm, but is not limited thereto, and may be configured by, for example, a cam. Further, the retard spring may be constituted by rubber or the like instead of the spring.

  In the present embodiment, the manual feed tray 560 is configured to be openable and closable with respect to the separation frame 570. The present invention is not limited to a monochrome laser printer, and may be applied to a full-color laser printer.

  20: Image forming unit (image forming unit) / 100: Image forming apparatus (printer) / 500: Sheet feeding device (manual feeding unit) / 510: Feeding unit (pickup roller) / 520: Conveying unit (feed roller) ) / 530: separation means (retard roller) / 540: support member (retard roller holder) / 542: other end / 550: biasing member (retard spring) / 560: stacking means (manual tray) / 562: locking portion / 570: Device main body (separation frame) / 580: Torque limiter / 590: Pressurizing means (pressurizing unit) / M: Drive source (motor) / N: Separation nip / S: Sheet

Claims (8)

The device body;
A stacking means that is movably supported with respect to the apparatus main body and stacks sheets;
A feeding means for feeding sheets stacked on the stacking means;
Conveying means for conveying the sheet fed by the feeding means;
Separating means for forming a separation nip portion in pressure contact with the conveying means, and separating the sheets fed by the feeding means one by one at the separation nip portion;
Pressurizing means for pressurizing the separating means to the conveying means,
The pressurizing means continuously changes the pressure applied to the conveying means of the separating means according to the position of the stacking means relative to the apparatus main body.
A sheet feeding apparatus characterized by that. The loading means is supported rotatably with respect to the apparatus main body between a closed position and an open position,
Sheets are stacked on the upper surface of the stacking means,
The sheet feeding apparatus according to claim 1. The pressure applied to the conveying means by the separating means decreases as the loading means approaches the closed position.
The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus. The pressurizing means includes a support member that movably supports the separation means, and an urging member that is stretched between the support member and the stacking means.
The sheet feeding apparatus according to claim 2, wherein the sheet feeding apparatus is a sheet feeding apparatus. The support member is a crank arm that rotatably supports the separation means at one end and is rotatably supported by the apparatus main body.
The biasing member is stretched between the other end of the crank arm and the loading means.
The sheet feeding apparatus according to claim 4, wherein the sheet feeding apparatus is a sheet feeding apparatus. The stacking means is provided at an end portion close to the separating means, and has a locking portion to which one end portion of the urging member is locked.
When the loading means moves toward the closed position, the locking portion moves in a direction approaching from the other end of the crank arm.
The sheet feeding apparatus according to claim 5, wherein The separation unit includes a drive source that inputs a drive in a direction opposite to the sheet conveying direction via a torque limiter.
The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device. A sheet feeding device according to any one of claims 1 to 7,
An image forming unit that forms an image on the sheet fed by the sheet feeding device,
An image forming apparatus.

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