JP2005053691A - Sheet feeding device and image processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of positively separating sheets with small, simple constitution and suppressing the formation of paper powder and power consumption. <P>SOLUTION: The sheet feeding device is provided with a separation roller 55 arranged facing a feed roller 52 and abutting on the sheet conveyed from a lead-in roller 51 to intercept the second sheet onward from the feed roller 52 side, and a torque limiter 55b provided at a rotary shaft of the separation roller 55 and having prescribed intercepting torque opposing in the rotating direction of the separation roller 55 following the sheet in feed. The intercepting torque is to be larger than torque received by the separation roller 55 by friction with the rotating feed roller 52 in a state of the sheet not being caught by a nip part between the feed roller 52 and separation roller, and to be smaller than torque received by the separation roller 55 by friction with the sheet in feed in a state of the sheet being caught by the nip part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheet feeding apparatus that is provided in an image processing apparatus such as a printer, a facsimile, or a copying machine, and that feeds a sheet such as a document or paper, and an image processing apparatus including the sheet feeding apparatus.

In an image processing apparatus such as a copying machine or a printer, a sheet such as a document or paper is fed from a sheet tray such as a document tray or a paper feed tray to an image reading unit or an image forming unit by a predetermined sheet feeding device.
This sheet feeding device picks up the sheets one by one by pressing and rotating a predetermined attracting roller (pickup roller) on the uppermost surface of the sheet placed on the sheet tray. Further, in order to prevent a plurality of sheets from being double-fed (carrying-feed), the picked-up sheet is fed with a predetermined feeding roller and a friction member such as a separating plate (friction pad) or separation roller (separating roller). The sheet is passed between (separating member), and the sheets are separated (separated) one by one and fed into the image processing apparatus.
Here, FIG. 4 is a cross-sectional view showing an example of a conventional sheet feeding device Z1 using a separating plate as the friction member.
As shown in FIG. 4, the conventional sheet feeding device Z1 feeds a sheet to the subsequent process by rotating and contacting the sheet conveyed from the preceding process (not shown). A separating plate 4 is elastically biased by a roller 3 (feeding roller) by an elastic member (SP (a)) such as a spring.
As a result, when a sheet is double fed between the sheet feeding roller 3 and the separating plate 4, the uppermost sheet (most sheet feeding roller 3 side) is fed to the subsequent process by the sheet feeding roller 3. The second and subsequent sheets are blocked by the frictional resistance of the separating plate 4.
FIG. 5 is a cross-sectional view showing an example of a conventional sheet feeding device Z2 using a separation roller as the friction member.
As shown in FIG. 5, the conventional sheet feeding device Z2 is a sheet feeding roller 3 (feeding roller) that feeds a sheet to a subsequent process by being rotationally driven in contact with the sheet conveyed from the attracting roller 2. ), A separation roller 4 ′ whose surface is formed of a predetermined high friction material is disposed oppositely, and the separation roller 4 is driven to rotate in a direction opposite to the direction in which the sheet feeding roller 3 is driven to rotate (reverse rotation). ).
As a result, as in the case of the sheet feeding device Z1, when a sheet has been double fed between the sheet feeding roller 3 and the separation roller 4 ′, the uppermost sheet is fed to the subsequent process by the sheet feeding roller 3. However, the second and subsequent sheets are blocked by the frictional resistance of the reversely rotating separation roller 4 ′.
Further, in Patent Document 1, when separating a plurality of recording sheets (sheets), a separating member (separation roller) is moved (rotated) in a direction opposite to the recording sheet conveying direction, and a separating member (feeding roller) is moved. ) Is moved following the Sabaki member (followed rotation), and after separation, the Sabaki conveying member is moved in the recording paper conveying direction, and the Sabaki member is also rotated in the recording paper conveying direction. .
JP-A-7-172711

However, in the conventional sheet feeding devices Z1 and Z2 that use a separating plate or convey a sheet while rotating the separating roller in reverse, the separating plate or separating roller and the sheet are separated in order to reliably separate (spread) the sheet. Although it is necessary to increase the friction coefficient, the sheet slides on the surface of the separating plate or separating roller having a large frictional resistance during sheet conveyance. For this reason, a drive source having a large torque, such as a large motor, is required for the paper feed roller, and there is a problem in that the apparatus becomes large and power consumption increases. Further, when the sheet is paper (recording paper, manuscript, etc.), there is a problem that a lot of paper dust is generated.
Further, in the conventional sheet feeding device Z2 that reversely rotates the separation roller (Sabakaki member) and the paper feeding device disclosed in Patent Document 1, a driving source for reversely rotating the separation roller is required, which complicates the device. There was a problem that this led to increased size, increased power consumption, and increased costs.
Accordingly, the present invention has been made in view of the above circumstances, and its object is to reliably roll (separate) a sheet with a small and simple configuration, as well as generation of paper dust and power consumption. It is an object of the present invention to provide a sheet feeding apparatus capable of suppressing the above-described problem.

In order to achieve the above object, the present invention provides a sheet feeding apparatus including a feeding roller that feeds a sheet to a subsequent process while rotating the sheet in contact with the sheet conveyed from the previous process and separating the sheets one by one. In the apparatus, a separating roller disposed opposite to the feeding roller and contacting the sheet conveyed from the previous process to block the second and subsequent sheets from the feeding roller side, and a rotating shaft of the separating roller And a torque limiter having a predetermined cutoff torque against a direction in which the separating roller is driven and rotated by the sheet being fed by the feeding roller.
As a result, even when the sheet comes into contact with the separating roller before the sheet is caught, that is, before the sheet is captured between the feeding roller (sheet feeding roller) and the separating roller, the torque limiter Since the forward rotation of the separation roller by the action (the direction of rotation following the sheet being fed) is suppressed, the second and subsequent sheets are blocked by the frictional force between the separation roller and the sheet, The sheet can be reliably rolled (separated).
Further, when the frictional force between the sheet and the separating roller during sheet feeding (conveying) is large and the torque applied to the separating roller by the frictional force exceeds the shut-off torque of the torque limiter, Since the roller rotates following the sheet being fed, the amount of paper dust generated is reduced, and the maximum torque applied to the drive source of the feeding roller, that is, the required maximum driving force is kept relatively small. Can do.
Moreover, since only a torque limiter is provided on the rotating shaft on the separating roller side, it is not necessary to provide a complicated mechanism such as a drive source or a clutch.

Here, the feeding roller and the separating roller are more reliably separated when the surfaces are arranged in contact with each other than when the feeding roller and the separating roller are arranged with an interval equal to or less than the thickness of one sheet. This is desirable.
In this case, the cutoff torque of the torque limiter is larger than the torque received by the separating roller due to friction with the feeding roller rotating in a state where a sheet is not captured between the feeding roller and the separating roller. If the torque is used, the rotation of the separating roller is suppressed during the sheet rolling (before the sheet is captured between the feeding roller and the separating roller), so that the sheet can be reliably rolled.
The torque limiter has a cut-off torque smaller than the torque received by the separating roller due to friction with the sheet being fed in a state where the sheet is captured between the feeding roller and the separating roller. If there is, the separating roller rotates while the sheet is being fed (conveyed) after the sheet is finished, so that the generation amount of paper dust and the power consumption of the feeding roller drive source can be further suppressed. .
Further, it is more preferable that the sheet feeding position by the feeding roller is arranged at a higher position than the sheet conveying position in the preceding process.
As a result, the sheet's own weight or the sliding of the sheet with respect to the inclined surface provided between the preceding process and the feeding roller contributes to the sheet rolling effect, thereby obtaining a higher sheeting effect.
In the present invention, the sheet feeding device may be regarded as an image processing device such as a printer, a facsimile, or a copying machine provided as a document feeding unit, a recording paper feeding unit, or the like.

According to the present invention, the separating roller is disposed on the rotary shaft of the separating roller that is disposed opposite to the feeding roller and contacts the sheet conveyed from the previous process and blocks the second and subsequent sheets from the feeding roller side. Is provided with a torque limiter having a predetermined cutoff torque that resists the direction of rotation of the sheet being fed by the feeding roller, so that even when the sheet abuts against the separating roller, By the action of the torque limiter, normal rotation of the separating roller (direction in which the sheet is rotated while being fed) is suppressed, and the sheet can be reliably wound (separated).
Furthermore, since the frictional force between the sheet and the separating roller during sheet feeding (conveying) is suppressed below the force corresponding to the cutoff torque by the action of the torque limiter, the amount of generated paper dust is reduced. In addition to the reduction, the driving source of the feeding roller can be reduced in size and power consumption.
Moreover, since only a torque limiter is provided on the rotating shaft on the separating roller side, it is not necessary to provide a complicated mechanism such as a drive source or a clutch, which is also effective for downsizing and power saving of the apparatus. is there.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a side sectional view showing a schematic configuration of an image forming apparatus including a sheet feeding apparatus X according to an embodiment of the present invention, FIG. 2 is a schematic side sectional view of the sheet feeding apparatus X, and FIG. FIG. 4 is a diagram for explaining the operation of the sheet feeding apparatus X, FIG. 4 is a schematic sectional side view of a conventional sheet feeding apparatus Z1 using a separating plate, and FIG. 5 is a conventional sheet feeding apparatus using a reverse rotating separating roller. It is a schematic sectional side view of Z2.

First, an image forming apparatus 1 (an example of an image processing apparatus) on which a sheet feeding apparatus X according to an embodiment of the present invention is mounted will be described using a side sectional view of FIG.
The image forming apparatus 1 has a copier mode (copying mode), a printer mode, and a FAX mode as print modes. An operation input from an operation unit (not shown) or a print job from an external host device such as a personal computer. Is selected by a control unit (not shown).
As shown in FIG. 1, the image forming apparatus 1 is roughly divided into a document reading unit 10 (document reading unit), a paper feeding unit 20 (paper feeding unit), a printing unit 30 (printing unit), and a paper discharge unit 40. The document reading unit 10 is disposed above the paper feeding unit 20, and the paper discharge unit 40 is disposed at an intermediate portion between the document reading unit 10 and the paper feeding unit 20.
Hereinafter, the copier mode will be described from the above processing modes.
After the user places a document on the platen glass 11 of the document reading unit 10 (scanner unit), the sheet (recording sheet) is placed on the sheet feeding cassette 21 of the sheet feeding unit 20 or the manual feed tray 23 provided on the side of the apparatus. After copying and inputting the condition input keys (number of prints / printing magnification, etc.) on the operation panel (not shown) arranged on the front of the exterior of the device, the copy operation is started by operating the start key on the operation panel. The
When the start key is operated, a main drive motor (not shown) starts and each drive gear rotates. Thereafter, the paper feed roller 22 or 22 a rotates to feed (feed) the paper into the apparatus, and the fed paper reaches the registration roller 31. The registration roller 31 temporarily stops the paper so as to synchronize with the leading edge (image formation start portion) of the image formed on the photosensitive drum 32, and the leading edge of the paper is uniformly pressed against the registration roller 31. Thus, the leading edge position of the paper is corrected.

On the other hand, in the document reading unit 10, the copy lamp 12a (light source) is turned on, and the exposure starts when the copy lamp unit 12 moves in the direction of the arrow. Irradiation light applied to the document by the copy lamp 12a becomes reflected light (reflected light from the document) including image information of the document, and the reflected light is transmitted from the first mirror 12b provided in the copy lamp unit 12 to the second light. Reading is performed by inputting to the CCD 16 from the mirror 13, the third mirror 14, and the optical lens 15.
The image information read in this way is converted into an electrical signal by a CCD circuit provided in a control unit (not shown), and the image information signal is subjected to image processing under a set condition. , And sent to the LSU unit 33 as print data.
On the other hand, the entire photosensitive drum 32 is charged to a predetermined charging potential by the charging unit 34. Laser light from the LSU unit 33 is irradiated to the photosensitive drum 32 through a polygon mirror and various lenses (not shown), and an electrostatic latent image is formed on the photosensitive drum 32. Thereafter, the toner on the MG roller 35 s in the developing tank 35 is attracted onto the surface of the photosensitive drum 32, and the electrostatic latent image is visualized by the toner according to the potential gap on the photosensitive drum 32.
In addition, a sheet (sheet) to be imaged is conveyed in the direction of the photosensitive drum 32 by the registration roller 31 in time, and the toner on the photosensitive drum 32 is transferred to the sheet by the transfer unit 36 (corona charger). The The toner remaining on the photosensitive drum 32 is scraped off by the cleaning blade 37 a of the drum unit and collected by the cleaner unit 37.

On the other hand, the paper on which the toner has been transferred passes through the upper heat roller 38a and the lower heat roller 38b of the fixing device 38 (fixing process), and heat and pressure are applied, so that the unfixed toner on the paper is melted into the paper. The paper is fixed and discharged to the paper discharge tray 42 by the paper discharge roller 41.
In addition, when a predetermined sensor detects that a document is placed on the document tray 19 of the sheet feeding device X provided in the document reading unit 10, the sheet feeding device X automatically supplies the document. The copy is executed.
That is, when the start key operation is performed, the drawing roller 51 (pickup roller) of the sheet feeding apparatus X rotates, and the document placed on the document tray 19 is sent into the document reading unit 10 to be predetermined. While the copy lamp unit 12 is stopped at a predetermined stop position, the document being conveyed is exposed. The process of reading the document image by the reflected light from the document obtained by this exposure is as described above.
The document whose image has been read in this way is discharged to the document discharge unit 18.

Next, the sheet feeding apparatus X according to the embodiment of the present invention will be described using the side view of FIG.
The sheet feeding apparatus X includes two rollers 51 and 52, and a sheet feeding unit 50 configured to be rotatable, and a rubber that is disposed to face one of the rollers and has a high coefficient of friction with respect to the sheet. A separating roller 55 having a surface formed of a material such as the like and a driving source (not shown) for driving the sheet feeding unit are provided.
The sheet feeding unit 50 rotates in contact with a document (sheet) placed on the document tray 19 and rotates to support the attracting roller 51 that picks up the document and to rotate the attracting roller 51. An arm member 53 and a rotatable roller that rotatably supports the arm member 53 on its rotation shaft 52a, and a sheet that is rotated by a drive source (not shown) and is sent from the pull-in roller 51. The sheet feeding roller 52 that feeds the image processing apparatus 1 into the image processing apparatus 1 while separating them one by one, and the rotational force of the sheet feeding roller 52 is transmitted to the drawing roller 51 to rotate the drawing roller 51. And an endless belt 54 which is an example of a rotational drive transmission means. The pull-in roller 51 approaches or separates from the document on the document tray 19 by the rotation of the arm member 53.
Here, the arm member 53 is supported by the rotation shaft 52a of the paper feed roller 52, and further receives a driving force of the rotation shaft 52a of the paper feed roller 52 via a coupling mechanism such as a clutch and rotates. It is configured as follows.
Further, the separation roller 55 is provided on the lower side of the paper feed roller 52 so as to face the paper feed roller 52, and a torque limiter 55b is provided on the rotation shaft 55a. The torque limiter 55b has a predetermined cutoff torque that resists the direction in which the separation roller 55 rotates following the document being fed by the paper feed roller 52 (clockwise in the figure). Here, the separating roller 55 is not connected to a driving source, and is free in a direction opposite to the sheet feeding direction.
The controller shown in the figure moves the drawing roller 51 from a predetermined retraction position A to the feeding position B where the document is fed in contact with the uppermost surface of the document (sheet) when feeding the document. , Control to return to the original retracted position A after feeding the document.
When the attracting roller 51 rotates in contact with the original, the original is fed (conveyed) along an inclined surface 59 that is obliquely upward in the original conveying direction, and the feeding roller 52 and the separating roller 55 are arranged on the inclined surface. The originals conveyed along the line 59 are conveyed one by one into the image processing apparatus 1 (post-process) while being separated one by one.
As described above, the sheet feeding position P2 by the sheet feeding roller 52 is positioned higher than the sheet feeding position P1 in the drawing roller 51 (an example of the preceding process), whereby the document Since the original weight and the sliding of the original with respect to the inclined surface 59 contribute to the original effect, a higher effect is obtained.

Next, the operation of the sheet feeding apparatus X will be described with reference to FIG.
First, in a state before the sheet (original) fed by the feeding roller 51 is captured between the paper feeding roller 52 and the separating roller 55 (hereinafter referred to as a nip portion), FIG. As shown in a), the sheet feeding roller 52 is driven to rotate in the sheet feeding direction, but the separating roller 55 is not driven but stopped.
This is because when the separation roller 55 is caused by the friction with the rotating sheet feeding roller 52 in a state where the sheet is not captured between the sheet feeding roller 52 and the separation roller 55, the breaking torque of the torque limiter is reduced. This is because the torque is larger than the received torque.
Thus, even when a plurality of sheets are multi-fed by the drawing roller 51, when the sheet passes between the sheet feeding roller 52 and the separating roller 55, the upper surface side and the lower surface side of the sheet The second and subsequent sheets other than the uppermost surface (the feed roller 52 side) are blocked by the separating roller 55 in a stopped state, and only the uppermost sheet is the above-described one. The sheet is caught between the sheet feeding roller 52 and the separating roller 55.
Next, while the sheet (original) captured between the paper feed roller 52 and the separating roller 55 is fed by the rotational force of the paper feed roller 52, as shown in FIG. In addition, the separation roller 55 rotates following the sheet being fed.
This is because when the sheet is captured by the nip portion, the torque applied to the separating roller 55 increases, but the cutoff torque of the torque limiter 55b is captured by the nip portion and is in friction with the sheet being fed. This is because the torque is smaller than the torque received by the separating roller 55.
In this way, after the separation of the sheet is completed, the separating roller 55 is driven to rotate, so that the generation of paper dust can be suppressed and the frictional force between the sheet and the separating roller 55 is the torque limiter. Since the force corresponding to the cutoff torque of 55b can be suppressed below, the drive source of the feeding roller 52 can be miniaturized and the power consumption thereof can be suppressed.
Moreover, since only the torque limiter 55b is provided on the rotating shaft on the separating roller 55 side, there is no need to provide a complicated mechanism such as a drive source or a clutch, which also reduces the size and power consumption of the apparatus. It is valid.
The sheet feeding apparatus X described above can be used as a sheet feeding apparatus for recording paper in the sheet feeding cassette 21 and the manual feed tray 23 in addition to feeding documents, and separates other sheets one by one. It can be applied to various devices that need to be fed.

  The present invention can be applied to various apparatuses such as an image processing apparatus that needs to separate and feed sheets one by one.

FIG. 2 is a side cross-sectional view illustrating a schematic configuration of an image forming apparatus including a sheet feeding device X according to an embodiment of the present invention. FIG. 3 is a schematic sectional side view of the sheet feeding apparatus X. FIG. 6 is a diagram for explaining the operation of the sheet feeding apparatus X. FIG. 6 is a schematic side cross-sectional view of a conventional sheet feeding device Z1 using a separating plate. FIG. 10 is a schematic side cross-sectional view of a conventional sheet feeding device Z2 using a reverse rotation separating roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Image reading part 18 ... Document discharge part 19 ... Document tray 20 ... Paper feed part 23 ... Manual feed tray 30 ... Printing part 31 ... Registration roller 32 ... Photosensitive drum 34 ... Charging unit 35 ... Developing tank 36 ... transfer unit 38 ... fixing device 40 ... sheet discharge section 50 ... sheet feeding section 51 ... calling roller 51a ... calling roller rotating shaft 52 ... feed roller 52a ... feed roller rotating shaft 53 ... arm member 54 ... Endless belt 55 ... separation roller 55a ... rotation shaft 55b of separation roller ... torque limiter 59 ... inclined surface

Claims (6)

In a sheet feeding apparatus including a feeding roller that feeds to a subsequent process while separating the sheets one by one by rotating and contacting the sheet conveyed from the previous process,
A separating roller disposed opposite to the feeding roller and damming the second and subsequent sheets from the feeding roller side in contact with the sheet conveyed from the previous process;
A torque limiter provided on a rotating shaft of the separating roller, and having a predetermined cutoff torque that resists the direction in which the separating roller is driven and rotated by the sheet being fed by the feeding roller;
A sheet feeding apparatus comprising:   The sheet feeding apparatus according to claim 1, wherein the feeding roller and the separating roller are arranged in contact with each other.   The shut-off torque of the torque limiter is larger than the torque received by the separating roller due to friction with the feeding roller rotating in a state where a sheet is not captured between the feeding roller and the separating roller. The sheet feeding apparatus according to claim 2.   The cutoff torque of the torque limiter is smaller than the torque received by the separating roller due to friction with the sheet being fed in a state where the sheet is captured between the feeding roller and the separating roller. Item 4. The sheet feeding device according to any one of Items 1 to 3.   5. The sheet feeding device according to claim 1, wherein the sheet feeding position by the feeding roller is disposed at a position higher than the sheet feeding position in the preceding process.   An image processing apparatus comprising the sheet feeding device according to claim 1.