JP2006124044A - Paper feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the lifetime of a paper feed roller, and to prolong the maintenance time of a paper feeder. <P>SOLUTION: In the paper feeder 9, a face side and a back side of a sheet is held by a paper feed roller 25 and a separation roller 26, and the sheet is fed by the friction force by rotating the paper feed roller 25. Thus, the nip pressure between the paper feed roller 25 and the separation roller 26 is adjusted by the magnetic force of a magnet by an electromagnet 37 provided inside the paper feed roller 25 and a magnetic material 38 provided inside the separation roller 26. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet feeding device that feeds a sheet material, and an image forming apparatus such as a copying machine, a printer, and a facsimile machine using the sheet feeding device.

  Conventionally, as a sheet feeding device that feeds a sheet material, one that feeds a sheet material sandwiched between a sheet feeding roller and a friction member by rotating the sheet feeding roller has been disclosed. Some of them are pressurized using a spring force in order to prevent double feeding of the sheet material and increase the conveying force. However, if a spring is used for the paper feed roller, the intended pressure setting may not be achieved due to changes in pressure due to changes over time or variations in the pressure of the spring itself, so a nip pressure is generated using a permanent magnet. A method has been proposed (see Patent Document 1).

JP-A-5-238573 (second page, FIG. 1)

  However, when a permanent magnet is used in the sheet feeding device of the image forming apparatus, for example, when the nip pressure changes due to the change in the type (thickness) of the sheet material, the nip pressure cannot be easily adjusted. The life of the paper feed roller was shortened, and frequent maintenance was required. Also, when a permanent magnet is used, the nip pressure cannot be easily removed or the nip cannot be released by turning the power ON / OFF like an electromagnet, so the work is difficult when performing JAM processing. It was.

  SUMMARY An advantage of some aspects of the invention is that it provides a paper feeding device capable of extending the life of a paper feeding roller and extending a maintenance period, and an image forming apparatus using the paper feeding device.

The invention according to claim 1 is a sheet feeding device that feeds the sheet material by friction force by sandwiching the front side and the back side of the sheet material by a sheet feeding roller and a pressing member, and rotating the sheet feeding roller.
A nip pressure adjusting means capable of adjusting a nip pressure between the paper feed roller and the pressing member by a magnetic force of an electromagnet is provided.

  According to a second aspect of the present invention, in the paper feeding device according to the first aspect, the nip pressure adjusting means is a combination of an electromagnet provided on the paper feeding roller and a magnetic material provided on the pressing member. To do.

  According to a third aspect of the present invention, in the paper feeding device according to the first aspect, the nip pressure adjusting means is a combination of a magnetic material provided on the paper feeding roller and an electromagnet provided on the pressing member. To do.

  According to a fourth aspect of the present invention, in the paper feeding device according to any one of the first to third aspects, the nip pressure adjusting means is permanent with an electromagnet provided so that the pressing member can be pressed against the paper feeding roller by a magnetic force. It is a combination with a magnet.

  According to a fifth aspect of the present invention, in the paper feeding device according to any one of the first to fourth aspects, the nip pressure adjusting means includes a support shaft that supports the pressing member and a magnetic force between the support shaft and the support roller. It is a combination with the electromagnet provided so that it could be pressed to.

  A sixth aspect of the present invention is an image forming apparatus, wherein the paper feeding device according to any one of the first to fifth aspects and an image forming unit that forms an image on a sheet material fed from the paper feeding device. It is characterized by comprising.

  According to the sheet feeding device of the present invention, by providing the nip pressure adjusting means capable of adjusting the nip pressure between the sheet feeding roller for feeding the sheet material and the pressing member by the magnetic force of the electromagnet, the type of the sheet material can be changed. The nip pressure can be easily adjusted by changing the current of the electromagnet even when the feed roller diameter changes due to change or wear of the feed roller. The period can be lengthened.

  Also, for example, when an electromagnet is used for the pressing member, at the time when the next sheet material bites into the nip part after separating one sheet material, the current value flowing through the electromagnet is reduced or the current is turned off. The load on the sheet feeding roller can be reduced by reducing the nip pressure.

  Furthermore, when JAM occurs, the JAM process can be easily performed by reducing or cutting off the value of the current flowing through the electromagnet.

  According to the image forming apparatus of the sixth aspect of the present invention, the image forming unit that forms an image on the sheet material fed from the sheet feeding device is provided, so that the sheet is fed one by one in the image forming unit. An image can be formed on a sheet material.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(Outline of configuration and operation of image forming apparatus)
FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus using a paper feeding device to which the present invention can be applied as viewed from the front side (user side).

  As shown in FIG. 1, an image forming apparatus 1 includes an image forming apparatus main body 2 configured in a box shape, a sheet feeding and conveying unit 3, and an image forming unit in the image forming apparatus main body 2 in order from the lower side. 4, a fixing unit 5, and a paper discharge unit 6 are provided.

  In the paper feeding / conveying section 3, a manual paper feeding device 7, a paper feeding cassette 8 for automatic paper feeding, a pickup roller 10, a paper feeding device 9, a conveying roller 11, and a registration roller 12 are arranged. Has been. In the paper feeding / conveying unit 3, a sheet material (copy paper, plastic film, etc.) fed from a manual paper feeding device 7, or a pick-up roller 10 from a paper cassette 8 for automatic paper feeding, a paper feeding device. The sheet material S fed by the sheet 9 is conveyed upward by the conveyance roller 11, the skew feeding is corrected by the registration roller 12, and is synchronized with a predetermined timing (a toner image formed on a photosensitive drum described later). At timing, the image forming unit 4 is supplied to the image forming unit 4 described below.

  The image forming unit 4 includes a photosensitive drum 13 that is rotationally driven in the direction of an arrow (clockwise in FIG. 1), a charging roller 14, an exposure device 15, and a developing device 16 that are arranged almost in sequence along the rotational direction. A transfer roller 17 and a cleaning device 18 are disposed. The image forming unit 4 forms a toner image on the sheet material supplied from the paper feeding / conveying unit 3 described above. That is, the photosensitive drum 13 uniformly charged by the charging roller 14 is exposed according to the image information by the exposure device 15 to form an electrostatic latent image. The electrostatic latent image is developed as a toner image with toner attached thereto by the developing device 16.

  The toner image formed on the photosensitive drum 13 is transferred by the transfer roller 17 to the sheet material supplied from the paper feeding / conveying unit 3 described above. The toner remaining on the photosensitive drum 13 after the toner image transfer (transfer residual toner) is removed by the cleaning device 18. The sheet material having the toner image fixed on the surface is conveyed to a fixing unit 5 described below.

  The fixing unit 5 includes a fixing roller 21 including a heater 20 and a pressure roller 22 pressed against the fixing roller 21. In the fixing unit 5, the sheet material S conveyed from the image forming unit 4, that is, the sheet material S carrying an unfixed toner image on the surface is nipped and conveyed by the nip portion between both rollers. At this time, the sheet material S is heated and pressurized at the nip portion, and the toner image is fixed on the surface.

  The paper discharge unit 6 is provided with a paper discharge roller 23 and a paper discharge tray 24. The sheet material S after the toner image is fixed is discharged onto a paper discharge tray 24 by a paper discharge roller 23.

Thus, the one-side image formation for one sheet material S by the image forming apparatus 1 is completed.
(Configuration of paper feeder)
FIG. 2 is an explanatory diagram of a state in which a sheet material is fed from the sheet feeding cassette 8. As shown in FIG. 2, the paper feeding device 9 for automatic paper feeding includes a paper feeding roller (paper feeding roller) 25 and a separation roller (pressing member) 26 supported by support shafts 33 and 34, respectively. Yes. Then, the pickup roller 10 rotates in the direction of the arrow in FIG. 2, calls the uppermost sheet material S in contact with the pickup roller 10, advances the sheet material S toward the sheet feeding device 9, and moves in the direction of the arrow. To feed.

  3 to 5 show an embodiment of the paper feeding device 9. 3 to 5, the pickup roller 10 and the paper feeding roller 25 are attached to the upper housing 27, and the separation roller 26 is attached to the lower housing 28. The separation roller 26 is rotatably supported by the support shaft 34, and a torque limiter 30 is in contact with one side portion in the axial direction. The torque limiter 30 applies a frictional force to the separation roller 26 in the direction opposite to the rotation direction. Stop rings 31 and 32 are locked to both ends of the separation roller 26 and the torque limiter 30 so as not to move in the axial direction.

  For example, an electromagnet (or magnetic material) is accommodated inside the separation roller 26, and for example, a magnetic material (or electromagnet) is accommodated inside the paper supply roller 25 facing the separation roller 26. . The electromagnet and the magnetic material constitute nip pressure adjusting means. Further, the support portions at both ends of the support shaft 34 are supported by the long holes 35 and 36 formed in the lower housing 28 so as to be close to or separated from the sheet feeding roller 25 side. For example, when an electric current is passed through the electromagnet through the support shaft 34, the separation roller 26 moves closer to the sheet feeding roller 25 side by a magnetic force and presses the sheet feeding roller 25 with a predetermined nip pressure. .

  For this reason, for example, even when the type of the sheet material changes or the diameter of the sheet feeding roller 25 changes due to wear of the sheet feeding roller 25 due to long-term use, the sheet feeding roller is changed by changing the current of the electromagnet. 25 and the separation roller 26 can be adjusted in nip pressure. Thereby, the wear of the paper feed roller 25 can be reduced, and the maintenance period can be extended accordingly.

  FIGS. 6A and 6B are diagrams simply showing the sheet feeding device 9. In FIG. 6, the paper feed roller 25 and the separation roller 26 are covered with rubber materials 42 and 43 at the outer peripheral portions, respectively. In addition, an electromagnet 37 is accommodated inside the paper feed roller 25, and a magnetic material 38 is accommodated inside the separation roller 26. When a current is passed through the electromagnet 37, the separation roller 26 moves closer to the sheet feeding roller 25 side by the magnetic force, and presses the sheet feeding roller 25 with a predetermined nip pressure.

  FIGS. 7A, 7B, and 8 are views showing an enlarged state of the sheet feeding device 9 shown in FIGS. 6A and 6B.

  7 and 8, the support shaft 33 supporting the paper feeding roller 25 is divided into a support shaft 33a and a support shaft 33b in the middle of the axial direction, and the support shaft 33a and the support shaft 33b are divided into shafts. It connects via the insulator 45 provided in the middle part of the direction, and the electromagnet 37 is attached to this connection part via the bearing 44. FIG. Then, the wiring is drawn out from the electromagnet 37 and this wiring is connected to the main body power supply 46. A support shaft 34 that rotatably supports the separation roller 26 is supported by inverted U-shaped bearings 47 at both ends in the axial direction. In addition, by providing the insulator 45 as in the present embodiment, it is possible to use the support shaft 33 in place of the electric wire by passing an electric current through the support shaft 33.

  As shown in FIG. 7B, the bearing 47 has an oval hole 48 that is open at one end (downward in the drawing), and the support shaft 34 that supports the separation roller 26 in the oval hole 48. Is inserted. The support shaft 34 is formed in a shape in which the cross-sections at both end portions in the axial direction are partially cut away from each other on the facing surface side. For this reason, the support shaft 34 can be brought close to or separated from the paper feed roller 25 side while the rotation is restricted by the bearing 47. The separation roller 26 houses a magnetic material 38 inside. For this reason, when an electric current is passed through the electromagnet, the separation roller 26 is moved toward the sheet feeding roller 25 by the magnetic force, and the sheet feeding roller 25 is pressed with a predetermined nip pressure. The separation roller 26 is given a frictional force in a direction opposite to the rotation direction of the separation roller 26 by a torque limiter 30.

  FIG. 9 is a diagram illustrating another embodiment of the paper feeding device 9. In FIG. 9, a frame 40 made of a magnetic material is provided so as to surround a support shaft 33 that supports the paper feed roller 25 and a support shaft 34 that rotatably supports the separation roller 26. An electromagnet 41 is provided in the vicinity. For this reason, when an electric current is passed through the electromagnet 41, the frame body 41 is attracted by the magnetic force, the support shaft 34 moves to the sheet feeding roller 25 side, and the separation roller 26 presses the sheet feeding roller 25 with a predetermined nip pressure. It has become. Note that the frame body 40 and the electromagnet 41 may be provided not only on one side in the axial direction of the support shafts 33 and 34 as shown, but also on both sides in the axial direction.

  FIGS. 10A and 10B are diagrams showing still another embodiment of the sheet feeding device 9.

  In FIG. 10, the separation roller 26 has a torque limiter 51 in contact with one side in the axial direction. The separation roller 26 is rotatably supported by a support shaft 34, and both ends of the support shaft 34 are supported by inverted U-shaped bearings 52. Electromagnets 50 are provided close to both ends of the support shaft 34 in the axial direction. Further, as shown in FIG. 10B, the bearing 52 has an oval hole 53 whose one end (downward in the figure) is open, and a support shaft that supports the separation roller 26 in the oval hole 53. 34 is inserted. The support shaft 34 is made of a magnetic material, and the cross-sections at both end portions in the axial direction are formed in a shape in which the opposed surfaces are partially cut. The support shaft 34 and the electromagnet 50 constitute nip pressure adjusting means.

  In this way, the support shaft 34 can be moved closer to or away from the paper feed roller 25 while the rotation is restricted by the bearing 52. For this reason, when an electric current is passed through the electromagnet 50, the support shaft 34 moves to the sheet feeding roller 25 side by a magnetic force, and the separation roller 26 presses the sheet feeding roller 25 with a predetermined nip pressure.

  11 and 12 show an embodiment of the paper feeding device 9 in which the paper feeding roller 25 and the separation pad 55 (58) are combined.

  FIG. 11 shows a state in which a separation pad 55 with an electromagnet 56 attached is disposed opposite to a paper feed roller 25 that houses a magnetic material 54 inside. Thus, when an electric current is passed through the electromagnet 56, the separation pad 55 is moved to the sheet feeding roller 25 side by a magnetic force, whereby the separation pad 55 presses the sheet feeding roller 25 with a predetermined nip pressure.

  FIG. 12 shows a state in which the separation pad 58 is disposed so as to face the sheet feeding roller 25 in which the electromagnet 57 is accommodated, and the magnetic material 60 is attached to the separation pad 58. Thus, when a current is passed through the electromagnet 57, the magnetic material 60 and the separation pad 58 are moved toward the sheet feeding roller 25 by a magnetic force, whereby the separation pad 58 presses the sheet feeding roller 25 with a predetermined nip pressure.

  13 and 14 show an embodiment of the paper feeding device 9 in which the paper feeding roller 25 and the separation pad 62 (68) are combined.

  FIG. 13 shows a state in which a separation pad 62 to which a permanent magnet 63 is attached is arranged so as to face the sheet feeding roller 25 whose outer peripheral portion is covered with a rubber material 42. Further, the permanent magnet 63 is accommodated in the guide frame 65 so as to be movable. Furthermore, an electromagnet 64 to which a battery 69 is connected is accommodated in a guide frame 65 so as to face the permanent magnet 63. For this reason, when an electric current is passed through the electromagnet 64, the separation pad 62 moves to the sheet feeding roller 25 side together with the permanent magnet 63 by the repulsive force of the magnet, and the separation pad 62 presses the sheet feeding roller 25 with a predetermined nip pressure. It has become.

  FIG. 14 shows a state in which an electromagnet 66 is housed inside the paper feed roller 25 and the electromagnet 66 is attached to the support shaft 33 via a bearing 67. Further, a separation pad 68 to which a magnetic material 70 is fixed is disposed so as to face the paper feed roller 25, and the magnetic material 70 is movably accommodated in a guide frame 71. For this reason, when an electric current is passed through the electromagnet 66, the separation pad 68 and the magnetic material 70 move toward the sheet feeding roller 25 by magnetic force, and the separation pad 68 presses the sheet feeding roller 25 with a predetermined nip pressure.

  INDUSTRIAL APPLICABILITY The present invention can be used as a sheet feeding device that feeds a sheet-like recording material to an image forming unit in the field of image forming apparatuses such as a copying machine, a facsimile machine, a printer, or a multifunction machine having both functions. .

1 is a schematic configuration diagram of an image forming apparatus using a paper feeding device according to the present invention as viewed from the front side. FIG. 10 is an explanatory diagram illustrating a state in which a sheet material is fed from a sheet feeding cassette. It is an external view of the attachment state of a paper feeder. It is an external view of the attachment state of a paper feeder. It is an external view of the attachment state of a paper feeder. (A) is a front view of a paper feeding device using a paper feeding roller and a separation roller, and (b) is a side view thereof. (A) is the front view which shows the detail of a paper feeder same as the above, (b) is the partial side view. FIG. 8 is a side view of FIG. It is a front view of a paper feed device using a paper feed roller and a separation roller. (A) is a front view of a paper feeding device using a paper feeding roller and a separation roller, and (b) is a partial side view thereof. It is a cross-sectional side view of a paper feeding device using a paper feeding roller and a separation pad. It is a cross-sectional side view of a paper feeding device using a paper feeding roller and a separation pad. It is a cross-sectional side view of a paper feeding device using a paper feeding roller and a separation pad. It is a cross-sectional side view of a paper feeding device using a paper feeding roller and a separation pad.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 4 ... Image forming part, 9 ... Paper feeding apparatus, 25 ... Paper feeding roller, 26 ... Separation roller, 33 ... Support shaft, 34 ... Support shaft, 37 ... Electromagnet 38 ...... Magnetic material, 41 ... Electromagnet, 50 ... Electromagnet, 54 ... Magnetic material, 55 ... Separation pad, 56 ... Electromagnet, 57 ... Electromagnet, 58 ... Separation pad, 60 ... Magnetic material 62 ...... Separation pad 63 ... Permanent magnet 64 ... Electro magnet 66 ... Electro magnet 68 ... Separation pad 70 ... Magnetic material

Claims (6)

In the sheet feeding device that feeds the sheet material with frictional force by sandwiching the front surface side and the back surface side of the sheet material with a sheet feeding roller and a pressing member, and rotating the sheet feeding roller,
A nip pressure adjusting means capable of adjusting a nip pressure between the paper feeding roller and the pressing member by a magnetic force of an electromagnet is provided.
A paper feeder characterized by that. The nip pressure adjusting means is a combination of an electromagnet provided on the paper feed roller and a magnetic material provided on the pressing member.
The paper feeding device according to claim 1. The nip pressure adjusting means is a combination of a magnetic material provided on the paper feed roller and an electromagnet provided on the pressing member.
The paper feeding device according to claim 1. The nip pressure adjusting means is a combination of an electromagnet and a permanent magnet that are provided so that the pressing member can be pressed against the sheet feeding roller by a magnetic force.
The paper feeding device according to any one of claims 1 to 3. The nip pressure adjusting means is a combination of a support shaft that supports the pressing member and an electromagnet provided so that the support shaft can be pressed against the sheet feeding roller by a magnetic force.
The paper feeding device according to claim 1, wherein the paper feeding device is a paper feeding device.   6. An image forming apparatus comprising: the sheet feeding device according to claim 1; and an image forming unit that forms an image on a sheet material fed from the sheet feeding device.

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