JP2011098822A - Sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a sheet feeder having a roller support rotatably installed on a driving shaft of a pickup roller and rotating the roller support around the driving shaft, thereby allowing the pickup roller to come into contact with a sheet on a sheet loading table, to feed the sheet; wherein, if an electromagnetic clutch or a device utilizing a mechanical load in a driving transmission system is employed as a means for holding the pickup roller in an escape position, power consumption in the sheet feeder increases when the mechanical load in the driving transmission system is intentionally increased, or when the electromagnetic clutch in a driving transmission system route is constantly kept in a connected state. <P>SOLUTION: A mechanism holding the pickup roller in an escape state is provided utilizing a magnetic material and a permanent magnet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet feeding device that feeds sheets of documents, recording materials, and the like stacked on a sheet stacking table such as a document tray or a sheet feeding tray one by one from the sheet stacking table.

  2. Description of the Related Art Conventionally, a sheet feeding apparatus used for a scanner, a copying machine, or the like has a roller support member rotatably attached to a drive shaft of a feed roller, and a pickup roller is attached to the front end side of the roller support member. By rotating around the roller driving shaft, the rotating pickup roller is brought into contact with the sheet on the sheet stacking table, and the sheet is sent out from the sheet stacking table by the pickup roller. When the sheet is not fed, the roller support member is rotated in the reverse direction to move the pickup roller to a retreat position where it does not contact the sheet on the sheet stacking table.

In such a sheet feeding device, there is one in which a roller support member is rotated by a solenoid. In addition, the roller drive shaft and the roller support member are connected via a spring clutch, the roller support member is rotated in conjunction with the roller drive shaft, and the roller drive shaft is operated while the roller support member is stopped. There is one that enables the relative rotation to rotate by the operation of a spring clutch (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2001-63855

However, in the case where the roller drive shaft and the roller support member are connected via the spring clutch described above, in order to hold the roller support member in the retracted position, when the drive of the roller drive shaft is stopped, The roller drive shaft must be stationary without rotating against the torque due to the working gravity. If the load such as mechanical friction of the drive system is small or an electromagnetic clutch for controlling the rotation of the pickup roller is used in the drive transmission path that transmits the drive force to the roller drive shaft, the drive of the roller drive shaft When stopped, the roller drive shaft rotates due to the weight of the pickup roller and the roller support member, the roller support member cannot be held in the retracted position, and it becomes an obstacle when the sheet is placed on the sheet stacking table. Occurs. In order to avoid this, if the load on the drive transmission system is deliberately increased or the electromagnetic clutch of the drive transmission path is always connected, the power consumption of the sheet feeding device increases and the environment is considered. It is no longer a product.

  The sheet feeding apparatus according to the present invention includes a pickup roller that feeds a sheet stacked on a sheet stacking table from the sheet stacking table, a separating unit that separates the fed sheets one by one, and a separation unit that cooperates with the separating unit. A sheet feeding device comprising: a feed roller that feeds the sheet into the apparatus; a roller drive shaft that drives the feed roller; and a roller holding member that holds the pickup roller. The pickup roller is rotatable about the roller driving shaft to a retracted position separated from the sheet stacking table, and the sheet feeding device includes a cover that covers the roller holding member, and a cover that covers the cover. A connection mechanism for connecting a roller holding member, and when the roller holding member is rotated to the retracted position, the connection mechanism causes the retracted position to be Characterized in that it is held in.

  According to the present invention, a pickup roller for feeding a plurality of sheets stacked on a sheet stacking table, a separating unit for separating the fed sheets one by one, and a sheet separated in cooperation with the separating unit into the apparatus. In a sheet feeding apparatus including a feeding roller to be fed and a roller holding member that pivotally supports a rotating shaft of the pickup roller and a rotating shaft of the feeding roller, the roller holding member is moved to a sheet stacking base without using wasteful power. Therefore, it is possible to provide an easy-to-use sheet feeding apparatus with low power consumption that can be reliably held at the retracted position away from the sheet.

1 is a diagram illustrating a schematic configuration of an image reading apparatus that is an embodiment of the present invention. 1 is a diagram illustrating a schematic configuration in the vicinity of a pickup unit of an image reading apparatus that is an embodiment of the present invention. FIG. It is a figure for demonstrating schematic structure of the pickup unit of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a sheet feeding apparatus that feeds sheets to be read such as originals one by one will be described as an example. However, the present invention is not limited to this, and for example, recording paper The same effect can be obtained even if the present invention is applied to a sheet feeding apparatus that feeds sheets to be recorded one by one.

In the following embodiments, an image reading apparatus will be described as an example of an image processing apparatus. However, the present invention is not limited to this, and image recording for recording an image on a sheet to be recorded such as a printer, for example. Image processing apparatus having an image processing unit, an image reading unit for reading an image on a sheet to be read and an image recording unit for recording an image on a sheet to be recorded, an image processing apparatus such as a facsimile machine, or a combination of these functions Other image processing apparatuses such as multifunction peripherals may be used, and the same effect can be obtained by applying the present invention to a sheet feeding apparatus used in the image processing apparatus.

In the following embodiments, a sheet feeding apparatus integrally provided in the image processing apparatus will be described as an example. However, the present invention is not limited to this, and is detachable from the image processing apparatus, for example. A sheet feeding apparatus may be used, and the same effect can be obtained by applying the present invention to the sheet feeding apparatus.

A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional side view showing an aspect of an image reading apparatus provided with a sheet feeding apparatus to which the present invention is applied.

In FIG. 1, 100 is an image reading apparatus, 100a is a sheet stacking unit for stacking and storing sheets S to be read such as originals, and 100b is a discharge stacking unit for stacking and storing the sheets S after image reading processing. A cover 100c covers the sheet conveyance path, and is supported so as to be openable and closable so that a jammed sheet can be taken out when a paper jam occurs. Reference numeral 111 denotes a pickup roller that sends out the sheets S stacked on the sheet stacking unit from the sheet stacking unit (sheet stacking table) 100a. Reference numeral 120 denotes a separation unit that divides a plurality of sheets into a single sheet, and includes a feed roller 113 that rotates forward in the conveyance direction and a separation pad (separation unit) 114 that cooperates with the separation roller 114 to separate the sheets. 121, 122, 123, and 124 are conveying rollers that convey the sheet S at a predetermined speed, and 131, 132, 133, and 134 are driven rollers that are arranged to be pressed against the conveying rollers 121, 122, 123, and 124, and are driven to rotate. Each drive roller and driven roller are paired to hold and convey the sheet. Reference numerals 140 and 150 denote image reading units, which can read the images of the front and back surfaces of the sheet S that have been sent. The separation means may be a separation roller.

FIG. 2 is an enlarged view of the vicinity of the pickup unit in the image reading apparatus 100. Reference numeral 10 denotes a pickup unit for feeding sheets stacked on the sheet stacking unit 100a into the image reading apparatus. The pickup unit 111 serves as a feeding unit and a roller holding member 112 for holding the pickup roller 111, which will be described later. The idler gear train 11 b is used to transmit the rotation of the feed roller 113 to the pickup roller 111.

The roller holding member 112 is supported on the drive shaft of the feed roller 113 and is rotatable about the drive shaft. The pickup roller 111 contacts the uppermost sheet S stacked on the sheet stacking portion 100a. It is movably supported between the contact position and a retreat position that does not hinder the stacking operation on the sheet stacking unit 100a.

A sheet-like permanent magnet 112 x is attached to the roller holding member 112 at a portion covering the pickup roller 111. An adsorption member 110d made of a magnetic material such as iron is held on the side facing the roller holding member 112 of the cover 100c so as to be movable in the vertical direction, and is attached to the lower side by a pressure spring 110s. It is energized. When the roller holding member 112 is moved to the retracted position, the pickup magnet 111 can be held at the retracted position by attracting the permanent magnet 112x provided on the roller holding member 112 to the attracting member 110d. Here, it is preferable that the attracting force F between the permanent magnet 112x and the attracting member 110d has a relationship of F> W with respect to the pressing force W due to gravity acting on the pickup unit 10. When the mechanical load that prevents the roller holding member 112 from being lowered when the driving of the roller is stopped is expressed by V, for example, the adsorption force F may be reduced within a range satisfying the relationship of F> W−V. Good.

FIG. 3 is a plan view of the pickup unit 10 including the pickup roller 111, the roller holding member 112, the feed roller 113, and the like. In order to facilitate understanding, the upper surface portion of the roller holding member 112 is shown through. An arrow X in the drawing indicates the conveyance direction of the sheet S.

A feed roller 113 is disposed at a substantially central portion of the roller holding member 112 in the vertical direction in FIG. As described above, the feed roller 113 is rotatably supported on the main body of the image reading apparatus 100 by the feed roller shaft 113a that is a roller drive shaft that passes through the roller holding member 112, and is rotated by the feed roller shaft 113a. Driven. Inside the side wall of the roller holding member 112 on the side of the feed roller 113, a feed roller gear 113b for transmitting the rotation of the feed roller shaft 113a to an idle gear train 11b described later is disposed. It is fixed.

A pickup roller 111 is disposed on the upstream side of the roller holding member 112 in the conveying direction (the right side in FIG. 3). The pickup roller shaft 111 a of the pickup roller 111 is rotatably supported by the roller holding member 112. A pickup gear 111b for transmitting rotation from an idle gear train 11b, which will be described later, to the pickup roller 111 is disposed on the inner side of the side wall of the roller holding member 112 on the side of the pickup roller 111, and is attached to the pickup roller shaft 111a. It is fixed.

Between the pickup gear 111b and the feed roller gear 113b, an idle gear train 11b that transmits the rotation of the feed roller shaft 113a to the pickup roller 111 is disposed at a position that meshes with the pickup gear 12b and the feed roller gear 113b. . As described above, by disposing the idle gear train 11b between the feed roller gear 113b and the pickup gear 111b, the feed roller 113 and the pickup roller 111 can be rotated in the same direction. Therefore, the pickup roller 111, the feed roller 113, and the separation pad 114 can feed and transport only one sheet S stacked on the uppermost side downstream in the transport direction.

On the outer side of the roller holding member 112 in the feed roller shaft 113a, when the feed roller shaft 113a is rotated in the direction opposite to the direction at the time of sheet feeding, the rotation of the feed roller shaft 113a in the reverse direction is the roller holding member. A rotation transmitting member 30 capable of transmitting to 112 is disposed. The rotation transmitting member 30 includes a roller holding member convex portion 112d, a first collar 31, a second collar 32, a first spring clutch 33, and a second spring clutch 34, which will be described later.

From the vicinity of the insertion portion 113c of the feed roller shaft 113a in the roller holding member 112, a convex portion 112d of the roller holding member 112 formed in a cylindrical shape encloses the feed roller shaft 113a in an upward direction in FIG. The first spring clutch 33 is formed so as to extend to the inside. The roller holding member 112 and the roller holding member convex portion 112d have an integral structure, and the feed roller shaft 113a is rotatable inside the roller holding member convex portion 112d. The first collar 31 formed in a cylindrical shape and disposed at a position adjacent to the roller holding member convex portion 112d in the upward direction in FIG. 3 is rotatably fitted to the feed roller shaft 113a. A partition wall 31a for isolating a first spring clutch 33 and a second spring clutch 34, which will be described later, is provided at a substantially central portion of the first collar 31.

A second collar 32 formed in a cylindrical shape is disposed at a position adjacent to the side of the first collar 31 that is far from the roller holding member convex portion 112d, and is inserted into and fixed to the feed roller shaft 113a. ing. A rib 32 a for preventing the second spring clutch 34 from falling off is provided at the end of the second collar 32. A first spring clutch 33 and a second spring clutch 34 are wound around the outer periphery of the first collar 31 and the second collar 32, respectively, and the rotation of the feed roller shaft 113a is transmitted to the roller holding member 112.

A first spring clutch 33 as a first clutch member formed in a substantially spiral spring shape is wound around the outer peripheral surface of the roller holding member convex portion 112d and the outer peripheral surface of the first collar 31 on the roller holding member convex portion 112d side. ing. In the first spring clutch 33, when the feed roller shaft 113a rotates in the sheet feeding direction, the spring loosens and the spring diameter increases, and conversely, the feed roller shaft 113a is in a direction opposite to the sheet feeding direction ( When rotated in the reverse direction), the spring is tightened and the spring diameter is reduced. That is, when the feed roller shaft 113a rotates in the sheet conveyance direction, the roller holding member convex portion 112d slides between the first collar 31 and the roller holding member 112 is independent of the rotation of the first collar 31. It can be rotated or stopped. Further, when the feed roller shaft 113a rotates in the reverse direction, the roller holding member convex portion 112d and the first collar 31 are integrally rotated or stopped.

The first spring clutch 33 has a spring shape and a strong force so that the spring remains tightened until the first predetermined torque is generated even when the feed roller shaft 113a rotates in the sheet feeding direction. Therefore, the first collar 31 and the roller holding member convex portion 112d continue to rotate or stop together. As described above, the rotation holding force is transmitted by the roller holding member convex portion 112d, the first collar 31, and the first spring clutch 33 until the first predetermined torque in the sheet feeding direction is generated. A torque limiter is configured. That is, if the torque is equal to or lower than the first predetermined torque, it can be transmitted by the first torque limiter.

Over both the outer peripheral surface of the first collar 31 extending to the side closer to the second collar 32 and the outer peripheral surface of the portion extending downward in FIG. 3 than the rib 32a of the second collar 32, Similar to the first spring clutch 33, a second spring clutch 34 is wound as a second clutch member formed in a substantially spiral spring shape. The second spring clutch 34 is wound in a winding direction opposite to that of the first spring clutch 33. When the feed roller shaft 113a rotates in the sheet conveying direction, the spring is tightened and the spring diameter is reduced. When the feed roller shaft 113a rotates in the reverse direction, the spring is loosened and the spring diameter is increased. That is, when the feed roller shaft 113a rotates in the sheet conveying direction, the first collar 31 and the second collar 32 rotate or stop together, and when the feed roller shaft 113a rotates in the reverse direction. The first collar 31 and the second collar 32 are configured to slide and rotate or stop separately.

However, the second spring clutch 34 has a spring shape and strength so that the spring remains tightened until the second predetermined torque is generated even when the feed roller shaft 113a rotates in the reverse direction. Therefore, the first collar 31 and the second collar 32 continue to rotate or stop together. When torque equal to or greater than the second predetermined torque is generated, it acts in the same manner as the first spring clutch 33, the spring loosens and the spring diameter increases, and the first collar 31 and the second collar 32 slide separately. It can be rotated or stopped. As described above, by the first collar 31, the second collar 32, and the second spring clutch 34, the second torque limiter that transmits the rotational drive until the second predetermined torque in the reverse direction is generated. It is configured. Note that the second predetermined torque may be equal to the first predetermined torque.

Next, the sheet feeding apparatus in the image reading apparatus according to the first embodiment of the present invention will be described in detail with reference to FIGS.

The user sets a sheet whose image is to be read on the sheet stacking unit 100a. When the image reading apparatus is in the standby state, the rotation driving of the feeding roller and the pickup roller is stopped, but the permanent magnet 112x provided on the roller holding member 112 is provided on the cover 100c so as to be movable up and down. Since it is adsorbed by 110d, the roller holding member 112 is connected to the cover 100c. At this time, the roller holding member 112 is stably held in the retracted position where the pickup roller 111 is separated from the sheet stacking portion 100a, and does not hinder the operation of setting the sheet. Thus, the permanent magnet 112x and the attracting member 110d are components of a connection mechanism that connects the cover 100c and the roller holding member 112, and the attracting force between them is the retaining force of the connection mechanism. Although it is preferable to include the pressure spring 110s as a component of the connection mechanism of the present embodiment, it is not essential. Note that the connection mechanism may use any force such as a force due to static electricity, a locking force due to Velcro (registered trademark) or a locking mechanism, or an adhesive force in addition to a magnetic force. Further, the permanent magnet 112x may be provided on the cover 100c, and the attracting member 110d may be provided on the roller holding member 112. Further, the pressure spring 110s may be provided on the permanent magnet 112x. The permanent magnet may be a plastic magnet.

Thereafter, when the image reading operation is started by the user's operation such as pressing the start button, a drive motor (not shown) starts rotating, and each transport roller starts rotating. Next, an electromagnetic clutch (not shown) that transmits rotational driving from a driving motor (not shown) to the feed roller shaft 113a is turned on. The electromagnetic clutch is connected and the driving force is transmitted to the feed roller shaft 113a.

As the feed roller shaft 113a rotates in the sheet conveying direction, the second collar also rotates together. Then, the spring of the second spring clutch 34 is tightened to reduce the spring diameter, and the first collar 31 and the second collar 32 are integrated to start rotating in the sheet conveying direction. When the first collar 31 starts to rotate in the sheet conveying direction, the first spring clutch 33 is loosened and the first collar 31 starts to slide relative to the first spring clutch 33. At this time, as described above, the first spring A first predetermined torque that is a loosening torque of the clutch 33 is transmitted. Due to the transmission of the first predetermined torque, the difference (F−W) between the aforementioned attractive force F of the permanent magnet 112 x and the pressing force W due to gravity acting on the pickup unit 10 is smaller than the pressing force acting on the pickup unit 10. The suction force F is set so that For this reason, when the feed roller shaft 113a rotates in the sheet conveying direction, the permanent magnet 112x is separated from the attracting member 110d, and the roller holding member 112 rotates toward the sheet stacking portion 100a.

As the roller holding member 112 rotates, the pickup roller 111 descends and comes into contact with the uppermost surface of the sheet S stacked on the sheet stacking unit 100a to pick up and convey the sheet S. Here, since the rotation of the roller holding member 112 is restricted by the pickup roller 111 coming into contact with the sheet S, the first spring clutch is loosened and the rotation of the first collar 31 is not transmitted to the roller holding member convex portion 112d. . Therefore, the force with which the pickup roller 111 pushes the sheet S is approximately the sum of the force with which the pickup unit 10 is pushed down by gravity and the force with which the feed roller shaft 113a transmits the first predetermined torque to push down the pickup unit 10. It becomes equal and stable feeding can be performed.

The sheet S that has been picked up and conveyed is sent to the separation unit 120 while pushing down the sheet regulating member 115, and is reliably rolled up by the separation pad 114, and is conveyed from the conveyance rollers 121 and 122 and the driven rollers 131 and 132. By being conveyed by each roller pair, it passes in a state of being in close contact with the front and back image reading units 140 and 150.

The image formed on the front or back surface of the sheet S is line-scanned when passing through the reading positions of the front and back image reading units 140 and 150, and is output to the outside as an electrical signal. After the image is read in this way, the sheet S is conveyed by each roller pair including conveyance rollers 123 and 124 and driven rollers 133 and 134, and is discharged to the discharge stacking unit 100b.

When the image reading of all the originals is completed, the feed roller shaft 113a is rotationally driven in the reverse direction. As described above, even when the feed roller shaft 113a rotates in the anti-sheet conveyance direction, the second spring clutch 34 remains tightened until a predetermined torque is generated. The rotation with the second collar 32 is started. When the first collar 31 rotates in the reverse direction, the spring is tightened and the spring diameter is reduced, thereby transmitting the rotation to the roller holding member convex portion 112d. As a result, the roller holding member 112 starts to rotate in the reverse direction, and the pickup roller 111 moves to the retracted position.

When the pickup roller 111 moves to the retracted position, the permanent magnet 112x provided on the roller holding member 112 is attracted to the attracting member 110d provided on the cover 100c, and the pickup roller 111 is held at the retracted position. The adsorbing member 110d is movable in the vertical direction with respect to the cover 100c and is pressed downward by the pressure spring 110s, so that even if the cover 100c varies in the height direction, Since the permanent magnet 112x and the attracting member 110d are always in close contact with each other, the pickup roller 111 is stably held at the retracted position.

As described above, the permanent magnet 112x provided on the roller holding member 112 is connected in close contact with the attracting member 110d. As a result, the pick-up roller 111 is retracted without taking a wasteful power consumption method such as intentionally increasing the mechanical load of the drive transmission system or keeping the electromagnetic clutch of the drive transmission path always connected. The roller holding member 112 can be stably held at the retracted position where the state is reached. Therefore, an easy-to-use sheet feeding apparatus with low power consumption can be provided.

DESCRIPTION OF SYMBOLS 100 Image reading apparatus 100a Sheet stacking part 100b Discharge stacking part 100c Cover 110d Adsorption member 110s Pressure spring 120 Separating part 10 Pickup unit 111 Pickup roller 111a Pickup roller shaft 111b Pickup gear 11b Idler gear train 112 Roller holding member 112x Permanent magnet 113 Feed roller 113a Feed roller shaft 113b Feed roller gear 114 Separation pads 121, 122, 123, 124 Conveying rollers 131, 132, 133, 134 Drive roller 140 Front surface reading unit 150 Back surface reading unit 30 Rotation transmitting member 31 First color 32 Second color 33 First 1 spring clutch 34 2 spring clutch

Claims (4)

A pickup roller that feeds out the sheets stacked on the sheet stacking table from the sheet stacking table;
Separating means for separating the fed sheets one by one;
A feed roller for feeding the separated sheet in cooperation with the separating means into the apparatus;
A roller drive shaft for driving the feed roller;
A sheet feeding device comprising a roller holding member for holding the pickup roller,
The roller holding member is rotatable about the roller drive shaft to a retracted position where the pickup roller is separated from the sheet stacking table,
The sheet feeding device includes a cover that covers the roller holding member;
A connection mechanism for connecting the roller holding member to the cover;
The sheet feeding device, wherein the roller holding member is held at the retracted position by the connection mechanism when rotated to the retracted position. Drive transmission means for transmitting rotational driving of the roller drive shaft to the roller holding member;
The force that the connecting mechanism exerts on the roller holding member at the retracted position includes the force by which the roller holding member holding the pickup roller is pushed down by gravity, and the roller holding member by the rotational drive transmitted by the drive transmission means. The sheet feeding device according to claim 1, wherein the sheet feeding device is smaller than a sum of the pressing force. The drive transmission means is a torque limiter capable of transmitting the rotational drive of the roller drive shaft in the sheet feeding direction to the roller holding member when the torque is equal to or less than a predetermined torque. The sheet feeding apparatus according to 2. The connection mechanism includes a permanent magnet provided on one of the roller holding member and the roller holding member, and a magnetic body provided on the other of the roller holding member and the roller holding member. The sheet feeding apparatus according to any one of claims 1 to 3, wherein at least one of the magnetic bodies is held so as to be movable in substantially the same direction as the rotation direction of the roller holding member.

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