JP2005104688A - Sheet feeding device and image forming device and image reading device equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact sheet feeding device capable of securely separating sheets from each other even when setting sheets roughly and feeding them and to provide an image forming device and an image reading device equipped with it. <P>SOLUTION: A separation part for separating sheets 25 loaded on a sheet loading means one by one is constituted by a sheet feeding means 33 for feeding sheets and a separation member 34 coming into pressure-contact with the sheet feeding means 33 so as to come into contact with and leave it. Travel amount of the separation member 34 in the direction in which it leaves the sheet feeding means 33 is regulated below stacked height of sheets 25 when the maximum number of sheets are stacked on the sheet stacking means by a regulation member 36a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet feeding apparatus, an image reading apparatus including the sheet feeding apparatus, and an image forming apparatus, and more particularly to a configuration of a separation unit that separates sheets fed by a sheet feeding unit.

  In an image forming apparatus such as a conventional copying machine or facsimile, or an image reading apparatus such as a scanner, sheets such as recording paper and documents stored in a sheet stacking unit are sequentially sent out one by one by a sheet feeding unit. A sheet feeding device that separates the sheets one by one by the separation unit and feeds them to the image forming unit or the image reading unit is provided.

  As such a sheet feeding apparatus, a sheet fed by a pickup roller is separated by a separation unit including a pickup roller which is a sheet feeding unit for feeding a sheet and a separation pad which is in pressure contact with the pickup roller. There are some that are separated and fed separately.

  FIG. 4 shows an example of a conventional sheet feeding apparatus having such a configuration. In the figure, 333 is a pickup roller, 334 is a separation pad, and the separation pad 334 is pressed against the pickup roller 333 by a spring 334a.

  Reference numeral 350 denotes a tray on which the sheet 325 is set. When the sheet 325 is set on the tray 350, the sheet 325 has an end portion in a direction orthogonal to the sheet feeding direction (hereinafter referred to as a width direction) by the slider 360. In addition to being regulated, the leading end is set in the form of abutting against the abutting portion 335 a formed on the paper feed frame 335.

  In such a configuration, even if the sheet 325 is set roughly, the sheet 325 hits the abutting portion 335a and does not enter the nip portion between the pickup roller 333 and the separation pad 334. Is not pushed down by the sheet 325.

  Here, after the sheet 325 is set in this way, when the feeding operation is started by the feeding operation command, the pickup roller 333 first rotates in the clockwise direction, and at the same time, rotates up and down on the lower end portion of the tray 350. A stopper (not shown) that presses down the movable intermediate plate 330 is removed, and thereby the intermediate plate 330 is pushed up by an intermediate plate spring (not shown) and moves in the direction of the pickup roller 333.

  As the intermediate plate 330 moves in this manner, the leading end of the uppermost sheet 325a is pressed against the rotating pickup roller 333, whereby the sheet 325a is fed out with feeding force, and thereafter The images are separated one by one by the separation pad 334 and conveyed to the image forming unit or the image reading unit.

  FIG. 5 shows another example of a conventional sheet feeding apparatus. In FIG. 5, reference numeral 430 denotes a pre-press contact arm arranged upstream of the separation pad 334 in the sheet conveying direction. Here, the preliminary press contact arm 430 is configured such that the front end portion is positioned on both sides of the separation pad 334 and a force pressing the sheet 325 against the pickup roller 333 is applied when the sheet 325 is set (for example, , See Patent Document 1).

  Then, in the sheet feeding apparatus having the preliminary press-contact arm 430 having such a configuration, when the sheet 325 is set and then the feeding operation is started by the feeding operation command, the pickup roller 333 rotates in the clockwise direction. . Here, since the leading end portion of the sheet 325 is pressed against the pickup roller 333 by the pre-pressing arm 430, when the pickup roller 433 rotates, the uppermost sheet 325a is fed with a conveying force and then separated. The sheets are separated one by one by the pad 334 and conveyed to the image forming unit or the image reading unit.

Japanese Patent Laid-Open No. 02-89731

  However, in such a conventional sheet feeding apparatus, for example, in the sheet feeding apparatus shown in FIG. 4, when the sheet 325 is set, the sheet 325 can be set loosely. The portion 335a is required, and the intermediate plate 330 is also required to press the sheet 325 against the pickup roller 333 during the printing operation. For this reason, an apparatus will become large and cost will also increase.

  Further, in the sheet feeding apparatus shown in FIG. 5, the abutting portion and the intermediate plate are unnecessary, so that the apparatus can be downsized and the cost can be reduced. However, if the sheet 325 is set roughly, for example, the sheet 325 When the sheet is set on the tray 350, the sheet 325 enters the nip portion between the pickup roller 333 and the separation pad 334 in a state of force when the hand is released before the setting is completed, that is, when throwing is performed. .

  Here, when the sheet 325 enters the nip portion between the pickup roller 333 and the separation pad 334 with the momentum applied in this manner, the separation pad 334 is pushed down by the momentum of the sheet 325, thereby setting the sheet 325. At this time, a plurality of sheets 325 exist between the pickup roller 333 and the separation pad 334, and it becomes impossible to form an appropriate separation pressure and separation structure.

  If it becomes impossible to form an appropriate separation pressure and separation structure in this way, it is impossible to feed paper, or a paper feeding failure such as feeding a large number of sheets in a single feeding operation. May occur.

  Therefore, the present invention has been made in view of such a current situation, and can be downsized, and can reliably separate and feed sheets even when sheets are set roughly. Another object of the present invention is to provide an image forming apparatus and an image reading apparatus provided with the same.

  The present invention provides a sheet feeding apparatus that separates and feeds sheets stacked on a sheet stacking unit one by one by a separation unit, and contacts the sheet feeding unit and the sheet feeding unit. A separation member that presses in a separable manner and constitutes the separation unit together with the sheet feeding unit, and regulates an amount of movement of the separation member in a direction away from the sheet feeding unit, and the sheet feeding The number of sheets entering between the means and the separating member is regulated.

  According to the present invention, in a sheet feeding apparatus that separates and feeds the sheets stacked on the sheet stacking unit one by one by a separation unit, the sheet feeding unit that feeds the sheet, and the sheet feeding unit A separation member that is press-contactable so as to come into contact with and separate from the sheet feeding unit and that constitutes the separation unit; and a regulating member that regulates a movement amount of the separation member in a direction away from the sheet feeding unit. The amount of movement of the separating member in a direction away from the sheet feeding unit is regulated by the regulating member to be equal to or less than a stacking height of the sheet when the maximum number of sheets are stacked on the sheet stacking unit. It is characterized by.

  As described above, according to the present invention, when the maximum number of sheets are stacked on the sheet stacking unit, the amount of movement of the separating member that presses and contacts the sheet feeding unit in the direction away from the sheet feeding unit is determined. By limiting the height of the sheet to less than or equal to the sheet stacking height, the size can be reduced, and even when the sheets are set roughly, the sheets can be reliably separated and fed.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a facsimile apparatus which is an example of an image forming apparatus provided with a sheet feeding apparatus according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 100 denotes a facsimile apparatus main body (hereinafter referred to as an apparatus main body). The apparatus main body 100 includes a lower cover unit 8 and an upper cover unit 9 provided on the upper portion of the lower cover unit 8.

  Here, the lower cover unit 8 includes a bottom plate 74 to which an electric board is attached, and a lower cover 24 that is provided on the top of the bottom plate 74 and functions as a frame of the apparatus main body 100.

  The lower cover 24 is constituted by a sheet feeding device that separates and feeds the sheets 25 supported one by one by a stacking tray 26 detachably provided on the apparatus main body 100 so that the rear end does not hang down. The ASF unit 2 (Auto Sheet Feeder), the image forming unit 3 for forming an image on the sheet 25 conveyed from the ASF unit 2, and the apparatus main body 100 are configured to be detachable and attached to the apparatus main body 100. The hand scanner unit 5 that forms a part of the document reading unit 12, the ADF unit 6 (Auto Document Feeder) that separates and feeds the document 28 one by one, and the document 28 conveyed from the ADF unit 6 A document reading unit 12 to be read is attached.

  Here, the ASF unit 2 presses against the pickup roller 33 which is a sheet feeding unit for feeding a plurality of sheets 27 set on the stacking tray 26 and the pickup roller 33 to separate the sheets 25 one by one. A separation pad 34 that is a separation member that can be rotated in the vertical direction constituting the separation portion, and a rotation center axis of the separation pad 34 are configured to be rotatable, and a plurality of sheets 25 are placed on the upper surface thereof. A pre-pressing arm 30 is provided, and a sensor (not shown) for detecting the leading edge of the sheet 25 that is separated and fed one by one is provided.

  Reference numeral 36 denotes an under guide that constitutes a lower guide surface of the sheet conveyance path, and in which a preliminary press contact arm 30 and a separation pad 34 related to the separation of the sheet 25 are rotatably held. Is attached to a paper feed frame 35 that holds the pickup roller 33 and the paper discharge roller 32 and guides the upper side of the sheet conveying path to the image forming unit 3 and guides the lower side of the sheet conveying path after the image forming unit 3. ing.

  Reference numeral 31 denotes a pre-pressure contact arm spring that urges the pre-pressure contact arm 30 that is a pre-separation member to rotate in the direction of the pickup roller 33. The pre-pressure contact arm spring 31 always separates the seat 25 from the pre-pressure contact arm spring 31. The pad 34 is urged so as to be brought into contact with the upstream side in the sheet feeding direction with respect to the portion contacting the pickup roller 33.

  Reference numeral 37 denotes a separation pad spring disposed between the separation pad 34 and the under guide 36, and the separation pad 34 that can be brought into contact with and separated from the pickup roller 33 by the separation pad spring 37 is similar to the pre-press contact arm 30. It is urged in the direction in which it is pressed against the pickup roller 33.

  Reference numeral 27 denotes a sheet cover which is a cover of the stacking tray 26. The sheet cover 27 stacks sheets to be discharged after an image is formed as will be described later and sets the document 28 set in the ADF unit 6. It is also a tray for holding. Reference numeral 29 denotes an opening (sheet insertion port) for inserting and stacking the sheet 25 into the apparatus main body 100.

  The image forming unit 3 also presses the ink film 40, a line head (TPH: Thermal Print Head) 41 having eight heating elements per mm in the width direction of the sheet 25, and the sheet 25 and the ink film 40 against the line head 41. A platen roller 42 for conveying the sheet 25 is also provided.

  A sheet discharge roller 32 for discharging the image-formed sheet 25 to the outside of the apparatus main body and a sheet discharge roller 32 are pressed against the sheet discharge roller 32 by a spring (not shown) downstream of the image forming unit 3. A driven pinch roller 38 is provided.

  The ADF unit 6 includes a separation roller 47, a separation piece 48 provided to be rotatable around a fulcrum 48a, a separation spring 50 that urges the separation piece 48 counterclockwise, and a separation piece 48 on the separation roller 47. And a document conveying mechanism configured to be in pressure contact with each other. A feed roller 49 and a feed roller 51 that is in pressure contact with the feed roller 49 by a spring (not shown) are provided downstream of the ADF unit 6.

  The document reading unit 12 as an image reading unit includes a CIS (contact image sensor) 53 that reads image information of the document 28 by direct contact with the sensor unit, and a reading white reference plate provided at a position facing the CIS 53. 54, the white level of the white reference plate 54 is read before the CIS 53 reads the document, and the output level of the read signal is corrected. It is configured to prevent fluttering of the document.

  Further, on the downstream side of the CIS 53, there is provided a discharge roller 55 and a driven roller 55a that is driven in pressure contact with the discharge roller 55, and a document transfer section 7 that transfers the document 28 on which an image has been read out of the apparatus main body. ing. The discharge roller 55 has a structure in which the discharge roller 55 and the driven roller 55a are pressed against each other by lifting the entire hand scanner unit 5 upward. In addition, a sensor (not shown) for detecting whether the hand scanner unit 5 is attached to or detached from the apparatus main body 100 is provided.

  On the other hand, the upper cover unit 9 constitutes an exterior of the apparatus main body 100 and a guide below the document conveyance path 107. The upper cover unit 9 includes buttons and an apparatus for operating the apparatus main body 100. An operation unit unit 15 including an operation panel unit 10 provided with a display unit 14 indicating the state of the main body 100 and an ADF frame unit 11 serving as a cover member functioning as an upper guide of the document conveyance path 107 is rotated. It is attached movably. In addition, the display part in a display part unit is comprised by the dot of 10,000 dots or more.

  In the figure, reference numeral 76 denotes a board such as a hook board, a system control board, and a cordless slave board on which a wireless unit is mounted. Each board 76 is attached to a bottom plate 74. Further, the power supply board 79 for supplying electricity to each device and each board and the NCU board on which a modular terminal (not shown) is mounted are temporarily held on the sheet metal 80 in an upright state, and the sheet metal 80 is fixed to the bottom plate 74. The structure is taken.

  And by setting such an electrical component as such a layout, the board | substrate 76 which has a high mounting component can be stood | placed back, and the height of the whole apparatus can be restrained low.

  Next, a document image reading operation of the facsimile apparatus configured as described above will be described.

  When reading a document image, first, the document 28 is set at a predetermined position by an opening 44 for setting the document 28 and a document slider 45 for regulating the width direction of the document 28 set. Next, when the document 28 is set in the opening 44 in this way and the completion of the setting of the document 28 is detected by the sensor 46, the operator presses a reading start button (not shown) provided on the operation panel unit 10.

  As a result, a reading motor (not shown) provided in the ADF unit 6 is rotationally driven, and accordingly, the separation roller 47 is driven in the document conveying direction. As a result, the document 28 is conveyed in the downstream direction of the document conveying direction while being rolled by the separation piece 48 that is in pressure contact with the separation roller 47, and thereafter, only the lowermost sheet is separated and the document reading is performed as indicated by an arrow D. It is conveyed to the section 12.

  Next, the document 28 separated by the ADF unit 6 in this manner is guided to the nip portion between the feeding roller 49 and the feeding roller 51, and is nipped and conveyed by the feeding roller 49 and the feeding roller 51. The Thereafter, when the leading edge of the document is detected by a sensor 52 provided downstream of the feeding roller 49, the reading motor is rotated after a predetermined number of steps and then stopped. As a result, the document 28 stops at a predetermined position before the CIS 53.

  Thereafter, the CIS 53 reads the shading data of the white reference plate 54 and corrects the output level of the read signal. When such correction is completed, the reading motor rotates again, transports the document 28 by a predetermined number of steps, reaches the reading line of the CIS 53, and then sequentially reads the lower surface of the document 28 line by line.

  Next, the document 28 that has been read is guided to the nip portion between the discharge roller 55 and the driven roller 55a and is nipped and conveyed, and is discharged out of the apparatus body through an opening 57 provided on the front surface of the apparatus body. When a plurality of documents 28 are set, thereafter, the reading motor is rotated until the sensor 46 detects that there is no document, and the ADF unit 6 separates and conveys the documents 28 one by one. Repeat the operation to read the image data.

  Next, an image forming operation of the facsimile apparatus will be described.

  When a signal for starting image formation is sent to the sheet 25, a sheet conveyance motor (not shown) is rotated, and the pickup roller 33 is rotated clockwise. At this time, as described above, the separation pad 34 rotatably held by the under guide 36 is pressed against the pickup roller 33 by the separation pad spring 37. Further, the preliminary press contact arm 30 that is rotatably held around the rotation center axis of the separation pad 34 receives a force in the direction of the pickup roller 33 by the preliminary press contact arm spring 31, whereby the leading end of the sheet 25 is It is in contact with the pickup roller 33.

  As a result, when the pickup roller 33 rotates in the clockwise direction, the sheet 25 is conveyed in the direction of arrow S, the lower layer sheet 25 is dammed by the separation pad 34, and the uppermost sheet 25 is separated one by one, It is conveyed to the image forming unit 3.

  Next, after the sheet 25 separated into one sheet is detected by a sensor (not shown), the sheet conveying motor is rotated by a predetermined number of steps, and the wedge portion is constituted by the platen roller 42 and the line head 41 that are stopped. Led to 39. At this time, by performing feed control so that the sheet 25 is slightly bent, a slight skew generated in the sheet 25 is removed when the sheet 25 is separated or when a pickup operation is started.

  Next, after the pickup roller 33 is stopped so that the slightly bent sheet 25 does not return to the back, the conveyance system is controlled so that the platen roller 42 and the paper discharge roller 32 are rotated.

  Then, the sheet 25 and the ink film 40 are sandwiched between the platen roller 42 and the line head 41 by the control of the conveyance system, and the sheet 25 is first loaded by a predetermined amount in order to ensure the set margin of the leading edge of the sheet 25. Transport. Thereafter, each heating element of the line head 41 is controlled in accordance with the image to be printed, and the heating element of the line head 41 instantaneously generates heat at the dots that need to be printed, and the ink of the ink film 40 is melted to the sheet 25. Transfer.

  Next, after forming an image for one line, the sheet 25 and the ink film 40 are conveyed by one line by the platen roller 42. Then, an image is formed on the sheet 25 by sequentially repeating this control.

  Next, image data for one page is completed in this way, or when a sensor (not shown) detects the trailing edge of the sheet 25 and conveys the sheet 25 by a predetermined number of steps, the trailing edge of the sheet is at the image forming position. Then, the image forming operation for one page of the sheet is finished, and the paper is discharged to the opening 43 provided above the sheet feeding port by the paper discharge roller 32 and the pinch roller 38, and the series of operations is finished. If there is image data for the next page, image formation is performed by repeating the above series of operations.

  By the way, in the present embodiment, in order to configure the apparatus main body 100 in a compact manner, the configuration in which the sheet front end is lifted by the intermediate plate as in the conventional example shown in FIG. As in the other conventional example shown in FIG. 5, the leading end of the sheet is lifted by using a pre-contact arm 30 that is movable and is always lifted.

  However, when such a pre-pressing arm 30 is used, when the sheet 25 is set roughly as described above, the separation pad 34 may be moved by the sheet 25 entering between the pickup roller 33 in some cases. As a result, the two or more sheets 25 are fed together, or conversely, the conveyance force is not sufficiently applied and the sheet is not fed. there is a possibility.

  Therefore, in the present embodiment, as a countermeasure, even if the sheet 25 is set loosely, the separation pad 34 is separated into the under guide 36 as shown in FIG. 2 so that the separation pad 34 is not pushed down more than necessary. When the pad 34 is pushed down by a predetermined amount, a rib 36a that contacts the back surface of the separation pad 34 is provided.

  By the way, when the sheets 25 are set roughly, the state in which the force that pushes down the separation pad 34 is most effective is when the sheets 25 are set to the maximum on the stacking tray 26, that is, when the maximum number of sheets 25 are set. It is.

  Here, for example, assuming that the maximum number of sheets 25 that can be stacked is 20, and the stacking height of the 20 sheets 25 is about 2 mm, this stacking height is defined as the movable range of the separation pad 34 in the present embodiment. The separation pad 34 is set to 1 mm from the state in which the separation pad 34 is in contact with the pickup roller 33 below.

  As a result, when the sheet 25 is set roughly, when the separation pad 34 is pushed down by 1 mm as shown by the broken line against the force of the separation pad spring 37 by the sheet 25 with momentum, that is, the separation pad 34 is moved to the pickup roller. When moved 1 mm away from 33, the rib 36 a, which is a regulating member provided in the under guide 36, comes into contact with the back surface of the separation pad 34.

  The separation pad 34 abuts against the rib 36a in this manner, so that the separation pad 34 can be prevented from being pushed open more than necessary. When the sheet 25 is set, the pickup roller 33 and the separation pad 34 A large number of sheets 25 do not exist between the two.

  In this configuration, a plurality of sheets 25 exist between the separation pad 34 and the pickup roller 33 until the rib 36a and the separation pad 34 come into contact with each other, and an appropriate separation pressure is set. It becomes a state that cannot be obtained. However, as shown in FIG. 2, since the sheet feeding path is curved by about 20 degrees with the separation pad 34 as a boundary, the sheet 25 is curved by the curvature of the sheet feeding path. The leading end side of the lower sheet is pressed against the separation pad 34 due to the rigidity. As a result, only the sheet 25 in contact with the pickup roller 33 is fed, and the sheets can be separated and fed one by one.

  As a result, the ASF unit 3 (sheet feeding device) can be reduced in size, and when the sheet 25 is set, the sheet 25 is separated without causing poor feeding even when a complicated operation such as throwing the sheet 25 is performed. The performance can be stabilized.

  That is, the sheet feeding device is configured by restricting the amount of movement of the separation pad 34 in the direction away from the pickup roller 33 to be equal to or less than the stacking height of the sheets 25 when the maximum number of sheets 25 are stacked on the stacking tray 26. In addition, the sheet 25 can be reliably separated and fed even when the sheet 25 is set loosely.

  By the way, in the description so far, the movement range of the separation pad 34 is restricted so that the feeding performance is not adversely affected, and the separation pad 34 may be pushed down by a predetermined amount or more even if the sheet 25 is set roughly. However, the present invention is not limited to this, and the same effect can be obtained even if the amount of the sheet 25 entering the separation portion is limited.

  FIG. 3 shows the configuration of the sheet feeding apparatus according to the second embodiment of the present invention in which the amount of the sheet 25 entering the separation unit is limited in this way so that the feeding performance is not adversely affected. FIG. In the figure, the same reference numerals as those in FIG. 2 denote the same or corresponding parts.

  Here, also in the present embodiment, in order to configure the apparatus main body 100 in a compact manner, the configuration in which the sheet tip is lifted by the intermediate plate as in the conventional example shown in FIG. The leading end portion of the sheet is lifted by using a pre-welding arm 30 that is rotatable and movable in a lifted state.

  However, when such a pre-press-welding arm 30 is used, there is no member that can reliably receive the weight of the sheet 25 when the seat 25 is set roughly. Therefore, as described above, when the seat 25 is set roughly, the preliminary press-contact arm 30 is pushed down against the force of the pre-press contact arm spring 31 in some cases, and thus the pre-press contact arm 30 is in this state. When pushed down, a large number of sheets 25 enter the nip portion (separation portion) between the pickup roller 33 and the separation pad 34.

  Therefore, in the present embodiment, the preliminary press-contact arm 30 is pushed down by a predetermined amount to the under guide 36 so that a large number of sheets 25 do not enter the nip portion between the pickup roller 33 and the separation pad 34 in this way. That is, a rib 36b is provided so as to come into contact with the rear surface of the front end of the pre-pressing arm 30 when the pre-pressing arm 30 moves a predetermined amount in a direction away from the pickup roller 33.

  By the way, when the sheets 25 are set roughly, the state where the force that pushes down the preliminary press-contact arm 30 most works is when trying to set the sheets 25 on the stacking tray 26 to the maximum, that is, trying to set the maximum number of sheets 25 to be loaded. It's time.

  Here, for example, assuming that the maximum number of sheets 25 that can be stacked is 20 and the stacking height of the 20 sheets 25 is about 2 mm, this stacking height is defined as the movable range of the preliminary press-contact arm 30 in the present embodiment. The pre-pressing arm 30 is set to 1 mm from the state in which the pre-pressing arm 30 is in contact with the pickup roller 33.

  As a result, when the sheet 25 is set roughly, when the pre-pressing arm 30 is pushed down by 1 mm as shown by the broken line by the sheet 25 with momentum, that is, the pre-pressing arm 30 is 1 mm away from the pickup roller 33. When moved, the rib 36 b, which is another restricting member provided in the under guide 36, comes into contact with the back surface of the preliminary press contact arm 30. The rib 36b abuts against the back surface of the pre-press contact arm 30 as described above, so that the under guide 36 receives most of the force that pushes down the separation pad 34 that occurs when the sheet 25 is set loosely. .

  The preliminary pressure contact arm 30 thus abuts on the rib 36b can prevent the preliminary pressure contact arm 30 from being pushed and opened more than necessary. As a result, when the sheet 25 is set, the pickup roller 33 is set. And a large number of sheets 25 do not enter between the separation pad 34 and the separation pad 34.

  That is, by controlling the gap between the pre-pressing arm 30 and the pickup roller 33, it is possible to control the amount of the sheet 25 that is pushed downstream from the pre-pressing arm 30.

  As a result, most of the force that pushes down the separation pad 34 of the sheet 25 can be reduced. As a result, the ASF unit 3 (sheet 25 feeding device) can be made compact, and the sheet 25 is set. At this time, even when a complicated operation such as throwing in the sheet 25 is performed, the separation performance can be stabilized without causing poor feeding.

  The configuration according to the present embodiment, that is, the configuration for reducing the force to push down the separation pad 34 by restricting the movement range of the preliminary press-contact arm 30, the first embodiment of the present invention described above. By applying to the sheet feeding apparatus according to the above, that is, by restricting the movement range of the preliminary press-contact arm 30, and further restricting the movement range of the separation pad 34, the feeding performance can be further stabilized. It becomes possible.

  In the description so far, the case where the pickup roller 33 and the separation pad 34 form the separation unit has been described. However, the present invention is not limited to this, and the separation roller is provided as a sheet feeding unit downstream of the pickup roller 33. The same effect can be obtained even when the separation portion is configured by pressing the separation pad 34 against the separation roller.

  In addition, the case where the present invention is applied to a sheet feeding apparatus provided in a facsimile apparatus which is an example of an image forming apparatus has been described so far. However, the present invention is not limited to this and is provided in an image reading apparatus. Needless to say, the present invention may be applied to a sheet feeding apparatus that feeds a sheet to the image reading unit.

1 is a diagram illustrating a schematic configuration of a facsimile machine that is an example of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention. The figure which shows the detail of the ASF part provided in the said facsimile apparatus. FIG. 4 is a diagram illustrating details of a sheet feeding apparatus according to a second embodiment of the present invention. The figure explaining the structure of an example of the conventional sheet feeding apparatus. The figure explaining the structure of another example of the conventional sheet feeding apparatus.

Explanation of symbols

2 ASF unit 3 image forming unit 12 document reading unit 25 sheet 26 stacking tray 30 preliminary press contact arm 31 pressing spring 33 pickup roller 34 separation pad 36 under guide 36a rib 36b rib 37 separation pad spring

Claims (10)

In a sheet feeding apparatus that separates and feeds sheets stacked on a sheet stacking unit one by one by a separation unit,
Sheet feeding means for feeding the sheet;
A separation member that pressably contacts the sheet feeding means and constitutes the separation unit together with the sheet feeding means;
With
The sheet feeding is characterized in that the amount of movement of the separating member in a direction away from the sheet feeding means is regulated, and the number of sheets entering between the sheet feeding means and the separating member is regulated. apparatus. In a sheet feeding apparatus that separates and feeds sheets stacked on a sheet stacking unit one by one by a separation unit,
Sheet feeding means for feeding the sheet;
A separation member that pressably contacts the sheet feeding means and constitutes the separation unit together with the sheet feeding means;
A regulating member that regulates a movement amount of the separating member in a direction away from the sheet feeding unit;
With
The amount of movement of the separating member in a direction away from the sheet feeding unit is regulated by the regulating member to be equal to or less than a stacking height of the sheet when the maximum number of sheets are stacked on the sheet stacking unit. A sheet feeding device characterized by the above.   A pre-separation member biased in the direction of the sheet feeding unit so that the sheet is brought into contact with the sheet feeding unit on the upstream side in the sheet feeding direction with respect to a portion where the separation member is in contact with the sheet feeding unit; The sheet feeding apparatus according to claim 2, further comprising a sheet feeding apparatus. Another regulating member that regulates the amount of movement of the pre-separation member in a direction away from the sheet feeding unit;
The amount of movement of the pre-separation member in the direction away from the sheet feeding unit by the other regulating member is less than the stacking height of the sheet when the maximum number of sheets are stacked on the sheet stacking unit. The sheet feeding device according to claim 3, wherein the sheet feeding device is regulated.   5. The sheet stacking unit stacks sheets in an inclined state, and the sheet enters between the sheet feeding unit and the separating member in an inclined state. The sheet feeding apparatus according to any one of the above.   The sheet feeding apparatus according to claim 1, wherein the sheet feeding path is curved with the separation portion as a boundary.   The sheet feeding apparatus according to any one of claims 1 to 6, wherein the sheet feeding unit feeds the sheets stacked on the sheet stacking unit.   The sheet feeding apparatus according to claim 1, wherein the sheet feeding unit feeds a sheet that has been fed out from the sheet stacking unit.   An image forming apparatus comprising: an image forming unit; and the sheet feeding device according to claim 1, wherein the sheet feeding device conveys a sheet to the image forming unit. An image reading apparatus comprising: an image reading unit; and the sheet feeding device according to any one of claims 1 to 8, which conveys a sheet to the image reading unit.

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