JP2016055978A - Standby feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a standby feeding device and an image forming apparatus, capable of effectively acquiring contact pressure around the center of a roller.SOLUTION: A standby feeding device 50 includes a standby conveyance roller pair composed of a ferromagnetic roller 51 made of a ferromagnetic material and a permeability roller 52 made of a material with a relative permeability of almost 1, and an external magnet 53 provided outside the rollers around the center of the standby feeding roller pair in an axial direction. The permeability roller 52 includes magnetism passing members 522 and 523 made of a ferromagnetic material provided at positions where the external magnet 53 forms a magnetic circuit so that magnetic lines of force produced by the external magnet 53 allow the standby feeding roller pair to produce contact pressure.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a standby conveyance device and an image forming apparatus.

2. Description of the Related Art Conventionally, printers and copiers having a registration roller mechanism including a driven roller and a driving roller have been proposed.
This registration roller is a stand-by transport roller that has the function of aligning the leading edge of the paper and refeeding it. However, when transporting very thick paper, the paper bites in by rotating the resist roller and the positional accuracy of the paper deteriorates. There was a case.
In the transport device of Patent Document 1, a pressure contact force is obtained with respect to the driven roller and the drive roller using a magnetic attraction force.

JP-A-6-199444

  However, in the configuration of FIG. 2 of Patent Document 1, since the roller pair is attracted by the electromagnets at both ends of the coil surrounding the shaft, many lines of magnetic force are generated from the outside of the coil at both ends of the shaft. The pressure contact force cannot be obtained effectively at the center. In addition, an excessive load causes problems such as warping of the roller and wear of the bearing. Furthermore, since the size of the coil is also limited by the thickness of the shaft, it is not practical.

  SUMMARY An advantage of some aspects of the invention is that it provides a standby conveyance device and an image forming apparatus that can effectively obtain a pressing force near the center of a roller.

  The standby transport device according to the present invention includes a standby transport roller pair having a ferromagnetic roller made of a ferromagnetic material and a magnetic permeability roller made of a material having a relative permeability of approximately 1, and a roller shaft of the standby transport roller pair An external magnet disposed outside the roller near the center, and the magnetically permeable roller has a magnetic passage member made of a ferromagnetic material provided at a position where the external magnet forms a magnetic circuit. The lines of magnetic force generated by the external magnets generate a pressure contact force on the standby conveyance roller pair.

  An image forming apparatus according to the present invention includes a standby conveyance roller pair having a ferromagnetic roller made of a ferromagnetic material and a magnetic permeability roller made of a material having a relative permeability of approximately 1, and a roller shaft of the standby conveyance roller pair. An external magnet disposed outside the roller near the center, and the magnetically permeable roller has a magnetic passage member made of a ferromagnetic material provided at a position where the external magnet forms a magnetic circuit. The lines of magnetic force generated by the external magnets generate a pressure contact force on the standby conveyance roller pair.

  According to the present invention, it is possible to provide a standby conveyance device and an image forming apparatus capable of effectively obtaining a pressing force near the center of a roller.

1 is a cross-sectional view illustrating an internal configuration of a full-color image forming apparatus according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the standby conveying apparatus which concerns on embodiment of this invention, (a) is a perspective view of a standby conveying apparatus, (b) is explanatory drawing of the magnetic passage member of a standby conveying apparatus. It is explanatory drawing of the standby conveying apparatus which concerns on embodiment of this invention. It is explanatory drawing of the standby conveying apparatus which concerns on other embodiment of this invention. It is explanatory drawing of the standby conveying apparatus which concerns on other embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

  FIG. 1 is a cross-sectional view illustrating an internal configuration of a full-color image forming apparatus (hereinafter simply referred to as a printer) according to an embodiment of the present invention.

  A printer 1 shown in FIG. 1 is an electrophotographic intermediate transfer tandem color image forming apparatus, and includes an image forming unit 2, a transfer belt unit 3, a toner supply unit 4, a paper feeding unit 5, and a belt type thermal fixing. It comprises a unit 6 and a transport unit 7 for duplex printing.

  The image forming unit 2 is in contact with the lower traveling portion surface 8a of the transfer belt 8 from the upstream side to the downstream side (same as above) in order to transfer the toner image to the lower traveling portion surface 8a of the transfer belt 8 by a so-called back transfer method. A configuration is adopted in which four image forming units 9 (9y, 9m, 9c, 9k) are arranged side by side in a multistage manner from the left side to the right side of the figure.

  Of the four image forming units 9, the three upstream image forming units 9y, 9m, and 9c are subtractive mixed primary color yellow (Y), magenta (M), and cyan (C) color toners, respectively. To form a monocolor image.

  The image forming unit 9k forms a monochrome image using black (K) toner mainly used for characters and dark portions of images. Each of the image forming units 9 has the same configuration except for the color of the toner for developing the image. Accordingly, the configuration of the image forming unit 9y for yellow (Y) toner will be described below as an example.

  The image forming unit 9 includes a photosensitive drum 10 as an image carrier at the top. The photosensitive drum 10 has a peripheral surface made of, for example, an organic photoconductive material. A cleaner 11, a charging roller 12, a writing head 13, and a developing roller 15 of the developing device 14 are disposed in contact with or surrounding the periphery of the photosensitive drum 10.

  The cleaner 11 includes a conveying screw inside, and waste toner that is removed from the peripheral surface of the photosensitive drum 10 and stays at the bottom is sent to a waste toner conveying path, which will be described later, by the conveying screw, and the waste toner is discharged to waste toner. The transport unit transports the waste toner to the waste toner collecting container 29.

  The developing device 14 includes a unit housing 16 that covers the outside, a partition wall 17 provided inside, a developing roller 15, a first stirring and conveying screw 18, and a second stirring and conveying screw 19. Although not specifically shown, the first and second agitating and conveying screws 18 and 19 include a screw shaft and a fin that is integrally formed with the screw shaft and rotates.

  The developing unit 14 includes a toner supply container 20 (20y, 20m, 20c, and 20k) of the toner supply unit 4, and yellow (Y) and magenta (M) as indicated by Y, M, C, and K in FIG. ), Cyan (C), or black (K) toner is supplied.

  The transfer belt unit 3 includes the above-described endless transfer belt 8 extending in a flat loop shape in the left-right direction in the figure at the approximate center of the apparatus main body, and the transfer belt 8 spanned over the transfer belt 8. A driving roller 21 and a driven roller 22 are provided to circulate and move counterclockwise as indicated by an arrow a in the figure.

  The transfer belt 8 includes a primary transfer roller 23 integrated with the unit. The primary transfer roller 23 is pressed against the photosensitive drum 10 via the transfer belt 8 and directly transfers (primary transfer) the toner image to the lower running portion surface 8a of the transfer belt 8 that circulates downward.

  The transfer belt 8 conveys the toner image to the paper secondary transfer unit 24 for further transfer (secondary transfer) to the paper. The secondary transfer unit 24 includes a transfer auxiliary roller 25 disposed on the downstream side (upward in the drawing) adjacent to the drive roller 21, and a secondary transfer roller 26 that is in pressure contact with the transfer auxiliary roller 25 via the transfer belt 8. And is formed.

  A belt cleaner 27 is disposed on the transfer belt 8. The belt cleaner 27 includes a cleaning blade 28 that contacts the surface of the transfer belt 8 that is stretched around the driven roller 22. A waste toner collection container 29 is detachably disposed adjacent to the belt cleaner 27 from the left to the bottom.

  The belt cleaner 27 scrapes off and removes the waste toner remaining on the surface of the transfer belt 8 by the cleaning blade 28 and sends the waste toner to a waste toner collection container 29 via a waste toner conveyance path described later.

  The toner supply unit 4 includes four toner supply containers 20 (20y, 20m, 20c, and 20k) that are detachably disposed above the upper running unit of the transfer belt 8. As described above, the four toner supply containers 20 contain yellow (Y), magenta (M), cyan (C), and black (K) toners.

  These four toner replenishing containers 20 are hidden behind the opposite side of the transfer belt unit 3 in FIG. 1 but are not visible, but each corresponding image forming unit 9 via a toner supply path following the toner supply port of the mounting portion. The developing device 14 is connected.

The paper feed unit 5 includes paper feed cassettes 30 arranged in two upper and lower stages. A paper take-out roller 31, a feed roller 32, a separating roller 33, and a standby conveyance device 50 are disposed in the vicinity of the paper feed opening (right side in the drawing) of the paper feed cassette 30.
The standby conveyance device 50 includes a ferromagnetic roller 51, a magnetic permeable roller 52, and an external magnet 53.

  In the paper conveyance direction (vertical upward direction in the drawing) of the standby conveyance device 50, the above-described secondary transfer portion 24 to the paper by the transfer belt 8, the transfer auxiliary roller 25, and the secondary transfer roller 26 is formed.

  A belt-type heat fixing unit 6 is disposed downstream (upward in the drawing) of the secondary transfer unit 24, and a sheet after fixing is fixed to the belt-type heat fixing unit 6 further downstream of the belt-type heat fixing unit 6. A pair of carry-out rollers 36 for carrying out the paper and a pair of paper discharge rollers 38 for discharging the carried paper to a paper discharge tray 37 formed on the upper surface of the apparatus are disposed.

  The conveyance unit 7 for double-sided printing also serves as an opening / closing member whose outer surface (right outer surface in the drawing) opens or shields the inside of the printer 1 from the side surface to the outside.

  The duplex printing transport unit 7 has a return start path 39a that branches rightward in the figure from immediately before the paper discharge roller pair 38, a return intermediate path 39b that bends downward, and a left lateral direction opposite to the above. Thus, a return path 39 including a return end path 39c for finally inverting the return sheet is provided.

  In the middle of the return path 39, five pairs of return rollers 41 (41a, 41b, 41c, 41d, 41e) are arranged. The exit of the return termination path 39c joins a conveyance path to the standby conveyance roller pair 34 corresponding to the sheet feeding cassette 30b below the sheet feeding section 5.

  2A and 2B are diagrams illustrating a standby transport device according to an embodiment of the present invention. FIG. 2A is a perspective view of the standby transport device, and FIG. 2B is an explanatory view of a magnetic passage member of the standby transport device. As shown in FIG. 2, the standby conveyance device 50 includes a ferromagnetic roller 51, a magnetically permeable roller 52, and an external magnet 53 as described above. The ferromagnetic roller 51 and the magnetically permeable roller 52 constitute a standby conveyance roller pair.

  The ferromagnetic roller 51 is made of a ferromagnetic material. For example, the ferromagnetic roller 51 is made of a ferromagnetic metal material such as iron. The ferromagnetic roller 51 has a roller shaft 511 and a bearing 512. The ferromagnetic roller 51 is provided with a receiving portion 61 that covers the outer periphery of the roller shaft 511, and the receiving portion 61 is biased in the direction of the magnetically permeable roller 52 by a biasing member 62. As a result, a pressing force is applied to the ferromagnetic roller 51 and the permeable roller 52. The biasing member 62 is biased by, for example, a compression coil spring. The urging member 62 is preferably disposed in the vicinity of both end positions of the roller portion of the ferromagnetic roller 51.

The permeable roller 52 is made of a material having a relative permeability of about 1. The magnetic permeability roller 52 is made of a metal material having a relative magnetic permeability close to 1, such as aluminum. The permeable roller 52 has a roller shaft 521 and a bearing 524, and a rotational force is applied to the roller shaft 521 by a driving device (not shown). The surface of the magnetic permeable roller 52 is coated with rubber.
Although the magnetic permeability roller 52 is made of aluminum, copper, titanium, austenitic stainless alloy or the like may be used as a metal material having a relative permeability close to 1.

  Further, magnetic passing members 522 and 523 made of a ferromagnetic material are disposed on the magnetically permeable roller 52 at positions where the external magnet 53 forms a magnetic circuit. The magnetic passage members 522 and 523 can efficiently pass magnetism, and the magnetic passage members 522 and 523 are made of an iron-based metal material, and the magnetic passage members 522 and 523 are provided. Thus, the attractive force between the ferromagnetic roller 51 and the permeable roller 52 can be increased with a small magnetic resistance.

  An external magnet 53 is disposed outside the magnetically permeable roller 52 in the vicinity of the center of the roller shaft of the standby conveyance roller pair. Here, an electromagnet is used as an example of the external magnet, but the present invention is not limited to this. The external magnet 53 has an arm portion 531 and a coil portion 532 made of a magnetic material, and generates a magnetic force by energizing the coil portion 532. The tip of the arm portion 531 is provided so as to be positioned in the vicinity of the magnetic passage members 522 and 523 of the magnetically permeable roller 52. As a result, a magnetic circuit is formed between the external magnet 53, the magnetic passing members 522 and 523 of the permeable roller 52, and the ferromagnetic roller 51, forming a magnetic line loop near the center of the roller, and the magnetic line generated by the external magnet 53. Generates a pressure contact force between the ferromagnetic roller 51 and the magnetically permeable roller 52 near the center of the registration roller pair. Further, since both ends of the ferromagnetic roller 51 and the permeable roller 52 are urged by the urging member 62, a pressing force is also applied to both ends of the ferromagnetic roller 51 and the permeable roller 52.

  As a result, when the sheet enters the standby conveyance device 50, the external magnet 53 is brought into a magnetic force generating state, and the rotation of the ferromagnetic roller 51 and the magnetically permeable roller 52 causes the leading edge of the sheet to be moved by the load generated by the magnetic lines of force. Can be stopped. At the time of re-feeding, the state of generation of the magnetic field lines is stopped, and the ferromagnetic roller 51 and the magnetically permeable roller 52 rotate with a normal load to convey the paper.

  FIG. 3 is an explanatory diagram of the standby conveyance device according to the embodiment of the present invention. FIG. 4A is a diagram for explaining an example in which a pressing force is applied only by an urging member, FIG. 4B is an explanatory diagram in the case where a magnetic passage member is not provided on the magnetic permeability roller, and FIG. The figure explaining the magnetic circuit of the standby conveying apparatus which concerns on this embodiment, (d) is a side view of (c).

  FIG. 5A shows an example in which the magnetically permeable roller 71 is not provided with a magnetic passage member, and the standby conveyance device 70 is not provided with an external magnet. In this case, since the pressure contact force between the permeable roller 71 and the ferromagnetic roller 51 is only the urging force of the urging member 62, the pressure contact force cannot be obtained near the center of the permeable roller 71 and the ferromagnetic roller 51.

FIG. 5B shows an example in which the standby conveyance device 80 is provided with the external magnet 53 and the magnetically permeable roller 81 is not provided with a magnetic passage member. In this case, even if an electric current is passed through the electromagnet as the external magnet 53, the magnetic resistance of the permeable roller 81 is large, so that a sufficient pressure contact force cannot be obtained near the center of the permeable roller 81 and the ferromagnetic roller 51.
Therefore, as in the present invention of FIG. 3C, by providing the magnetic passing members 522 and 523 in the magnetic permeable roller 52, the magnetic permeable roller can have a small magnetic resistance when a current is passed through the electromagnet as the external magnet 53. A sufficient pressure contact force can be obtained near the center of 52 and the ferromagnetic roller 51.

  4A is an explanatory view of a standby transfer device according to another embodiment of the present invention, and FIG. 4B is a sectional view thereof. In the standby conveyance device 90 shown in FIG. 4, in order to further reduce the magnetic resistance, there is a gap between the permeable roller 52 and the end surface 933 in the direction of the permeable roller 52 of the arms 931 constituting both ends of the electromagnet as the external magnet 93. A concave partial cylindrical surface having a minute gap is formed in accordance with the outer peripheral shape of the magnetically permeable roller 52 so as to be reduced. With this configuration, the magnetic resistance between the external magnet 93 and the permeable roller 52 can be reduced.

  FIG. 5 is an explanatory diagram of a standby transfer device according to another embodiment of the present invention. In the standby conveyance device 100 shown in FIG. 5, the external magnet 93 is provided below the magnetic permeable roller 52, and the ferromagnetic roller 51, the magnetic permeable roller 52, and the external magnet 93 are arranged in an L shape. Not limited to the example shown in FIG. 5, a magnetic circuit can be formed around the axis of the permeable roller 52.

  According to the above embodiment, a material that is not a ferromagnetic material is used for one of the rollers, a magnetic passage member is provided outside the center of the roller shaft, and only a part of the roller is strong so as to form a loop of magnetic field lines near the center of the roller. A magnetic member is provided. According to this configuration, the pair of standby transport rollers conventionally required a large load to keep the positional accuracy of many sheets such as thin paper, thick paper, and special paper constant, but the external magnet 53 as in the embodiment of the present invention. , 93, and by using an electromagnet and switching between ON and OFF, the positional accuracy of the paper can be stabilized without applying an excessive load. Also, by forming a loop of magnetic lines near the center of the roller, it is possible to effectively obtain a pressure contact force near the center where the load of the roller pair becomes insufficient. Further, since it is not necessary to install an electromagnet at the end of the shaft, the pair of rollers becomes long and the machine does not become large in the paper width direction. In addition, it is possible to stabilize the positional accuracy of the paper with respect to the image even with thick paper while preventing warpage of the standby conveyance roller due to a heavy load, preventing abnormal noise due to bearing wear, and reducing image blurring.

  In this embodiment, an electromagnet is used as the external magnet 93, but a permanent magnet may be used. In that case, by moving the permanent magnet or by providing a new magnetic circuit forming member made of a ferromagnetic material and bringing it close to the permanent magnet, the amount of magnetic force lines involved in the pressure contact of the roller pair is changed, and the pressure contact force of the roller pair Can be changed.

  The standby conveyance device and the image forming apparatus of the present invention are not limited to the above-described embodiments, and appropriate modifications and improvements can be made. Inventions with such modifications and improvements also include the present invention. It is included in the technical scope.

The invention described in the scope of claims attached to the application of this application will be added below. The item numbers of the claims described in the appendix are as set forth in the claims attached to the application of this application.
<Claim 1>
A pair of standby conveying rollers having a ferromagnetic roller made of a ferromagnetic material and a magnetically permeable roller made of a material having a relative permeability of about 1;
An external magnet disposed outside the roller in the vicinity of the center of the roller shaft of the standby conveyance roller pair,
The magnetic permeability roller is provided at a position where the external magnet forms a magnetic circuit, and has a magnetic passage member made of a ferromagnetic material,
The standby conveying apparatus, wherein the magnetic lines of force generated by the external magnet generate a pressing force on the standby conveying roller pair.
<Claim 2>
The standby transfer device according to claim 1, wherein the external magnet is an electromagnet.
<Claim 3>
A pair of standby conveying rollers having a ferromagnetic roller made of a ferromagnetic material and a magnetically permeable roller made of a material having a relative permeability of about 1;
An external magnet disposed outside the roller in the vicinity of the center of the roller shaft of the standby conveyance roller pair,
The magnetic permeability roller is provided at a position where the external magnet forms a magnetic circuit, and has a magnetic passage member made of a ferromagnetic material,
Magnetic lines of force generated by the external magnet generate a pressure contact force on the standby conveyance roller pair.
An image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 50, 90, 100 Standby conveyance apparatus 51 Ferromagnetic roller (a part of standby conveyance roller pair)
52 Permeable roller (part of standby transport roller pair)
522, 523 Magnetic passing member 53, 93 External magnet

Claims (3)

A pair of standby conveying rollers having a ferromagnetic roller made of a ferromagnetic material and a magnetically permeable roller made of a material having a relative permeability of about 1;
An external magnet disposed outside the roller in the vicinity of the center of the roller shaft of the standby conveyance roller pair,
The magnetic permeability roller is provided at a position where the external magnet forms a magnetic circuit, and has a magnetic passage member made of a ferromagnetic material,
Magnetic lines of force generated by the external magnet generate a pressure contact force on the standby conveyance roller pair.
A standby transfer device characterized by that.   The standby transfer device according to claim 1, wherein the external magnet is an electromagnet. A pair of standby conveying rollers having a ferromagnetic roller made of a ferromagnetic material and a magnetically permeable roller made of a material having a relative permeability of about 1;
An external magnet disposed outside the roller in the vicinity of the center of the roller shaft of the standby conveyance roller pair,
The magnetic permeability roller is provided at a position where the external magnet forms a magnetic circuit, and has a magnetic passage member made of a ferromagnetic material,
Magnetic lines of force generated by the external magnet generate a pressure contact force on the standby conveyance roller pair.
An image forming apparatus.

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