JP2005265003A - Rotation stabilizing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation stabilizing device capable of stabilizing rotations by restraining fluctuations in rotation generated by a drive transmitting member for transmitting driving force, with a simple and inexpensive structure. <P>SOLUTION: The rotation stabilizing device comprises a rotating element, a drive transmitting member provided on a rotating shaft of the rotating element and transmitting the driving force driving the rotating element, and an inertial member directly attached to the drive transmitting member. A plurality of attaching portions for attaching the inertial member to the drive transmitting member are integrally provided with the drive transmitting member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotation stabilizing device that suppresses rotation fluctuations of a photosensitive drum that carries an image or a reading pulley that moves an optical system that reads a document, and stabilizes the rotation, and an image forming apparatus including the rotation stabilizing device About.

  In recent years, stabilization of a rotating device has been desired in various technical fields. For example, a photosensitive drum that is used in an image forming apparatus such as a copying machine and carries an image is rotationally driven by a gear or the like. At this time, the vibration of the one-tooth component of the gear is transmitted to the photosensitive drum, and if the rotational fluctuation occurs in the photosensitive drum, the image is not uniformly formed, and the image quality may be deteriorated.

  In order to prevent such rotation fluctuations, it has been conventionally known to provide a disk-like inertia member coaxially with a gear, and various patent documents are disclosed.

  As an example of this, there is disclosed a rotation stabilizing device coupled with a rotating member and an inertia member that rotate via a grommet (viscoelastic member) having viscosity and elasticity (see Patent Document 1).

  The rotation stabilizer will be described with reference to FIG. 7. A photosensitive drum (not shown) is attached so as to rotate integrally with the left side of the drum shaft 92, and is not shown on the right side of the drum shaft 92. A gear 93 and a flyhole 95 that are rotated by a motor are attached to rotate integrally. An inertia member 96 is connected to the flyhole 95 via a grommet 97, a cylindrical sleeve 98 having a flange, and a bolt 99. With such a configuration, the natural frequency of the inertia member 96 and the grommet 97 is made close to the natural frequency of the gear 93, the flyhole 95, and the drum shaft 92, whereby the vibration of the gear 93 and the like can be damped.

  In addition, a rotation stabilizer that removably couples a rotating member and an inertia member that rotate via a viscoelastic member having viscosity and elasticity, and the attachment position of the viscoelastic member can be arbitrarily selected from a plurality of positions. Is disclosed (see Patent Document 2).

Furthermore, a rotary drive device is disclosed in which a ring-shaped inertial body (inertial member) having an inertial moment is attached to the outer periphery of a photosensitive drum as a rotating body via an elastic body (Patent Document 3).
JP 2001-50249 A JP 2002-5237 A JP 2001-188438 A

  As described above, it is important to stabilize the vibration of the photosensitive drum, but considering that the rotation stabilizer is mounted on the image forming apparatus and commercialized, it is also very important that the cost is not increased. . Considering each of the aforementioned patent documents from this point of view, the cost is inevitably high. That is, in patent document 1, in order to attach an inertia member, the grommet formed from the material which has viscosity and elasticity, a sleeve, and a screw are required. Moreover, in patent document 2, in order to attach an inertia member, the coupling member which has the collar part formed from the rotation member formed by the disk shape, and the material which has viscosity and elasticity is required. Furthermore, in patent document 3, in order to attach an inertia member, a ring-shaped elastic body is required.

  The present invention has been made in view of such a problem, and suppresses fluctuations in rotational speed caused by a drive transmission member that transmits a driving force to stabilize rotation, and viscoelastic members such as grommets as in the prior art. It is an object of the present invention to provide a rotation stabilizing device that is simple and inexpensive, and an image forming apparatus including the rotation stabilizing device.

  A rotating body, a drive transmission member that is provided on a rotation shaft of the rotating body and transmits a driving force that drives the rotating body, and an inertia member that is directly attached to the drive transmission member, and the drive transmission member A rotation stabilizing device comprising a plurality of mounting portions for mounting the inertia member integrally with the drive transmission member.

  According to the rotation stabilizer of the present invention and the image forming apparatus including the rotation stabilizer, the mounting portion provided integrally with the drive transmission member without separately providing a viscoelastic member such as a grommet as in the prior art. Since the inertia member is attached, the rotation can be stabilized by suppressing the fluctuation of the rotation speed caused by the drive transmission member that transmits the drive force with a simple and inexpensive configuration.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a rotation stabilizer of the present invention will be described with reference to the drawings.

  First, an example of an image forming apparatus provided with the rotation stabilizing device of the present invention will be described with reference to the block diagram of FIG.

  The image forming apparatus has an automatic document feeder 1 at the top of the main body. The main body includes an image reading means 2, an image writing means 53, an image forming means 3, a paper feeding means 5, a paper discharge refeeding means 6, and The fixing unit 7 and the like are included.

  The automatic document feeder 1 feeds documents placed on the document placing table 11 one by one to the document conveying means 13 by the document separating means 12, and the document conveying means 13 conveys the sent documents to the document discharging means 14. Then, the document discharge means 14 discharges the sent document to the document discharge table 15. The document image is read by a slit 21 provided in the document conveyance path, which is a document image reading position of the image reading unit 2.

  When reading images on both sides of the document, the document which has been read on the first surface is reversed by the document reversing means 16 having a pair of rollers, and is sent again to the document conveying means 13 to re-feed the second surface. Reading is done. The document that has been read is discharged to the document discharge table 15.

  The image reading unit 2 is a unit for reading an original image and obtaining image data. The original image irradiated with the light by the lamp 231 at the position of the slit 21 is a first mirror unit 23, a second mirror unit 24, and the like. An imaging lens 25 forms an image on an image sensor 26 that is a linear CCD. The signal output from the image sensor 26 is A / D converted by the image processing unit of the control unit C1, subjected to processing such as shading correction and image compression, and stored as image data in the memory M1.

  The image writing means 51 is a photosensitive drum 31 that is rotated by being uniformly charged by a charging means 52 with a laser beam and a polygon mirror based on image data that has been called from the memory M1 and subjected to predetermined image processing. The electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive drum 31 by scanning the surface.

  In the image forming unit 3, the electrostatic latent image is reversely developed by the developing unit 53, and a toner image is formed on the photosensitive drum 31.

  Corresponding to the above-described operation, the sheet P is fed from the manual sheet feeding unit 65 or the sheet feeding unit 5 having a cassette or tray for storing the sheet P as a recording material, and is conveyed by the conveying roller 54 and is sent to the timing roller. 59 is synchronized with the toner image formed on the photosensitive drum 59 and sent to the transfer area.

  In the transfer area, the toner image formed on the surface of the photosensitive drum 31 is transferred to the paper P charged to the opposite polarity by the transfer means 55.

  The sheet P carrying the toner image is separated from the surface of the photosensitive drum 31 by the action of the separation / elimination means 56 and sent to the fixing means 7.

  In the fixing unit 7, the paper P carrying the toner image is conveyed while being heated and pressurized by the heating roller 71 and the pressure roller 72, and after the toner image is fixed on the paper P, the conveyance roller 61 and the discharge roller 63. As a result, the sheet is discharged to a discharge tray 64 outside the apparatus.

  When the paper P is turned upside down and discharged onto the paper discharge tray 64, the paper P is guided to the paper discharge refeed means 6 by the switching guide 62, and the paper P is switched back and sent to the discharge roller 63. .

  Further, when forming an image on both sides of the paper P, the paper P that has been fixed on the first side is guided to the paper discharge refeed means 6 by the switching guide 62 and reversed by the reversing unit 65. Then, the sheet is fed to a conveyance path 66 for paper feeding and used for image formation on the second surface.

  On the other hand, the residual toner is removed from the surface of the photosensitive drum 31 after the transfer of the toner image onto the paper P by the cleaning means 57, and preparation for the next image formation is made.

  In the image forming apparatus as described above, the photosensitive drum 31 is driven by a motor (not shown) through a plurality of gears. At this time, vibrations caused by the gears are transmitted to the photosensitive drum 31, and there is a risk of fluctuations in rotational speed. A rotation stabilizing device configured to stabilize rotation by suppressing such fluctuations in rotational speed and at low cost will be described below.

  FIG. 2 is a side view of the rotation stabilizer, and FIG. 3 is an exploded perspective view of the rotation stabilizer.

  In FIG. 2, reference numeral 31 denotes the above-described photosensitive drum (rotating body), and a gear 41 (drive transmission member) is attached to a rotating shaft 31 a of the photosensitive drum 31. A rotational driving force of a motor (not shown) is transmitted to the gear 41 through a plurality of intermediate gears 43. Accordingly, the photosensitive drum 31 is rotated by the rotation of the gear 41.

  The gear 41 is molded from engineering plastic such as polyacetal or polycarbonate, and a plurality of mounting portions 42 are erected on the side surface by integral molding as shown in FIG. An inertia member 44 formed in a disk shape from a metal such as iron, aluminum, or brass is attached to a predetermined attachment portion 42.

  The plurality of attachment portions 42 are arranged on a circle provided around the rotation center of the gear 41 and are arranged on a plurality of concentric circles having different distances from the rotation center. In FIG. 2, the plurality of attachment portions 42 are arranged on a double circle, but may be arranged on a triple or more circle, or in some cases, may be arranged on only one circle. . The plurality of attachment portions 42 may have different thicknesses, and may have different heights.

  However, at least three attachment portions 42 having the same thickness and the same height are arranged on an arbitrary circle, and the attachment portions 42 having the same thickness and the same height arranged on the same circle. The inertia member 44 is attached to the head. Four or more mounting portions 42 having the same thickness and the same height may be arranged on the same circle. However, in order to obtain a uniform moment of inertia, each mounting portion 42 is placed on the same circle. It is desirable to arrange at equal positions.

  In FIG. 3, three thickest attachment portions 42a are equally arranged on the inner circle 41a at intervals of 120 degrees, and an attachment portion 42b slightly narrower than the attachment portion 42a is provided on the outer circle 41b. Three are arranged equally. Three attachment parts 42c that are thinner and shorter than the attachment part 42b are equally arranged on the outer circle 41b at a position shifted by 60 degrees with respect to the attachment part 42a, and the attachment part is provided on the inner circle 41a. Three attachment portions 42d that are thinner than the attachment portions 42c and have the same length as the attachment portions 42c are arranged equally. Therefore, in FIG. 3, four types of attachment portions 42 can be selected three by three.

  When the appropriate inertia member 44 is attached to the predetermined attachment portion 42, a large portion is provided at the portion of the inertia member 44 facing the other attachment portion 42 so that the other attachment portion 42 does not contact the inertia member 44. Make a hole.

  In FIG. 3, the inertia member 44 is attached to the attachment portion 42 b, and a hole 44 b that fits into the attachment portion 42 b is drilled in a portion of the inertia member 44 that faces the attachment portion 42 b. Then, the hole 44b is fitted into the mounting portion 42b, and a star washer (a spring washer having irregularities around the hole) 45 is fitted from the top as shown in FIG. Turn into. In addition, since each attachment part 42 is formed in the taper, the position of a height direction is decided with the diameter of the hole provided in the inertia member 44. FIG. In addition, large 44a, 44c, and 44d holes that do not come into contact with the respective mounting portions 42 are formed in portions of the inertia member 44 that face the mounting portions 41a, 42c, and 42d.

  Further, by changing the diameter of the hole to be fitted in the inertia member 44 to the same mounting portion 42, it can be mounted at different positions in the height direction of the mounting portion 42.

  As described above, the attachment portion 42 to which the inertia member 44 is attached can be selected from the attachment portions 42 having different distances from the rotation center of the gear 41 or different thicknesses, and the attachment height of the inertia member 44 can also be selected.

  In this way, it is appropriate to perform experiments beforehand so that the natural frequency when the mounting portion 42 and the inertia member 44 are integrated substantially matches the frequency of the gear 41 that rotates and vibrates by meshing teeth. An appropriate attachment portion 42 is selected, and an inertia member 44 corresponding to the attachment portion 42 is attached to the attachment portion 42. In this way, by making the frequencies substantially coincide with each other, a dynamic damper effect for suppressing resonance occurs. That is, since the attachment portion 42 is made of plastic, it has a certain degree of viscosity and elasticity, and the vibration of the gear 41 is converted to heat and attenuated by the deformation of the attachment portion 42. Therefore, the rotation variation of the gear 41 can be suppressed with a simple and inexpensive configuration, and the rotation can be stabilized.

  Note that the natural frequency increases when the position of the attachment portion 42 to which the inertia member 44 is attached is distant from the rotation center of the gear 41, and the natural frequency increases when the thickness of the attachment portion 42 is increased. Increasing the mounting height reduces the natural frequency.

  In addition, the natural frequency formed by the inertia member 44 and the attachment portion 42 is desirably set within a range of ± 10% around the frequency of one tooth of the gear 41.

  In FIG. 3, various mounting portions 42 having different distances, thicknesses, and heights from the rotation center of the gear 41 are erected on the gear 41. Only the distance may be varied, and the same attachment portion 42 may be erected with respect to the thickness and length. Furthermore, as a result of accumulating experiments in advance, if it is possible to grasp the distance, thickness and height from the appropriate rotation center of the gear 41 in the mounting portion 42, a predetermined thickness and height can be obtained on one circle. Only three or more attachment portions 42 may be disposed.

  In addition, since the natural frequency varies depending on the outer diameter and thickness of the inertia member 44, a plurality of inertia members 44 having different outer diameters and thicknesses may be provided and attached to the same mounting portion 42 as appropriate. .

  In the rotation stabilizing device described above, one inertia member 44 is provided on one surface of the gear 41. However, the inertia member 44 may be provided on both surfaces of the gear 41, respectively. The rotation stabilizer constructed as described above is shown in FIGS.

  FIG. 4 is a side view of the rotation stabilizing device. The photosensitive drum 31 and the inertia member 44 are the same as those shown in FIG. 2, but only the gear 46 is different. That is, the attachment portions 47 are provided on both surfaces of the gear 46, and the inertia member 44 can be attached to each of them.

  Accordingly, in the mounting portions 47 on both sides, the distance from the center of the gear 46 is different, the thickness is different, or the mounting height is different, so that the inertia member 44 is mounted on the both sides differently. When it is attached to 47, it has two natural frequencies, and even when the rotational speed of the gear 46 is changed, it is possible to cope with vibrations caused by two different rotational speeds.

  In addition, the inertia member 44 may be attached to one side or both sides of the gear, but if a cylindrical viscoelastic member is inserted into the attachment portion 47, the selection range of the natural frequency is further expanded. . Here, elasticity refers to the property that when the applied load is removed and stress is removed, the strain disappears and returns to its original shape. Viscosity moves one layer of fluid relative to the other. As a result of adhesion force and cohesive force, it refers to the property of generating internal friction along the boundary surface and resisting flow, and natural rubber or synthetic rubber is used as the material of the viscoelastic member.

  Since the gear 46 and the mounting portion 47 are integrally molded, if there is a thick portion, sink marks or the like occur and the gear machining accuracy deteriorates. Therefore, it is desirable to provide relief portions so that the overall thickness is substantially uniform, and a gear 46 provided with relief portions on both sides is shown in FIGS. FIG. 5 is a front view of the gear 46, and FIG. 6 is a cross-sectional view of the gear 46.

  In FIG. 5, the mounting portion 47 provided on one surface and the mounting portion 47 provided on the other surface are offset from each other by an angle of 30 degrees. Accordingly, relief portions 46a are provided on both surfaces as shown in FIG. 6 so as not to interfere with both attachment portions 47.

  In the rotation stabilizing device described above, the attachment portion is provided on the gear as the drive transmission member. However, the attachment is not necessarily limited to the gear, and a belt pulley that rotates the toothed belt may be used.

  Further, in the above rotation stabilizing device, the rotation is stabilized for the photosensitive drum 31 as the rotating body, but the present invention is not necessarily limited to the photosensitive drum 31 alone. For example, in FIG. 1, the second mirror unit 24, which is a part of the optical system for reading a document, is moved by a wire or the like, but the reading pulley that rotates the wire needs to be stably rotated. You may adapt to a reading pulley.

  In addition, any member of an image forming apparatus or another apparatus that is intended to stabilize rotation by suppressing fluctuations in rotational speed falls within the scope of the present invention. It is.

FIG. 2 is a configuration diagram of an example of an image forming apparatus in FIG. 1. It is a side view of a rotation stabilizer. It is a disassembled perspective view of a rotation stabilizer. It is a side view of the rotation stabilizer which attached the inertia member to both surfaces of the gearwheel. Front view of gear with relief It is sectional drawing of the gearwheel which provided the escape part. It is a side view of the rotation stabilizer in patent documents 1.

Explanation of symbols

31 Photosensitive drum 41, 46 Gear 42, 42a, 42b, 42c, 42d, 47 Mounting portion 44 Inertial member 45 Star washer

Claims (14)

A rotating body,
A drive transmission member that is provided on a rotating shaft of the rotating body and transmits a driving force for driving the rotating body;
An inertia member that is directly attached to the drive transmission member,
A rotation stabilizing device, wherein a plurality of attachment portions for attaching the inertia member to the drive transmission member are provided integrally with the drive transmission member. The vibration generated by the rotation of the drive transmission member is damped by the vibration of the attachment portion and the inertia member rotating at substantially the same frequency as the vibration of the drive transmission member. Rotation stabilizer. The rotation stabilizer according to claim 1, wherein the attachment portion is made of resin. The rotation stabilizer according to any one of claims 1 to 3, wherein the attachment portion is integrally formed with the drive transmission member. The rotation stabilizing device according to claim 1, wherein the drive transmission member is a gear or a belt pulley. At least three attachment portions are equally arranged on one or both surfaces of the drive transmission member on a circle centered on the rotation center of the drive transmission member, and the inertia member is attached to the attachment portion. The rotation stabilizer according to any one of claims 1 to 5, wherein The rotation stabilizer according to claim 6, wherein at least three attachment portions are equally arranged on the plurality of concentric circles, and the inertia member is attached to the attachment portions on the same circle. . The mounting portions having different thicknesses are arranged on the same circle or different circles, and the inertia member is mounted on the mounting portions having the same thickness on the same circle. The rotation stabilizer according to claim 7. Mounting portions of different lengths are arranged on the same circle or different circles, and the inertia member is mounted on the same thickness and the same length on the same circle. The rotation stabilizer according to claim 8. The rotation stabilizing device according to any one of claims 6 to 9, wherein the attachment height of the inertia member is variable with respect to the same attachment portion. The rotation stabilizer according to any one of claims 1 to 10, wherein a viscoelastic member is inserted into an outer peripheral surface of the attachment portion. The rotation stabilizer according to claim 1, wherein the rotating body is a photosensitive drum that carries an image or a reading pulley that moves an optical system that reads an original. 13. When the plurality of attachment portions are arranged on both surfaces of the drive transmission member, the positions of the attachment portions on both surfaces are made different from each other, and the lightening is performed. The rotation stabilizer according to any one of the preceding claims. An image forming apparatus comprising the rotation stabilizer according to claim 1.

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