JP2013155855A - Rotary damper and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary damper that effectively prevents transmission of vibration and an image forming device having the rotary damper.SOLUTION: A vibration preventing section 75 has a plurality of deformation sections 77 (77a-77c). The deformation sections 77 (77a-77c) are formed of first, second and third viscoelastic bodies, respectively. The modulus of elasticity of each of the first to third viscoelastic bodies which are deformed by rotating power, changes with time. When a rotary damper 70 transmits a use drive torque within a predetermined range to a photoreceptor drum 13, the rotary damper 70 changes with time to generate a state where both deformation sections 77a, 77b are compressively deformed instead of a state where only the deformation section 77a is compressively deformed. When the rotary damper 70 further changes with time, the deformation sections 77a-77c can be compressively deformed instead of a state where the deformation sections 77a, 77b are compressively deformed.

Description

  The present invention relates to a rotary damper and an image forming apparatus having the rotary damper.

  2. Description of the Related Art Conventionally, in a driving device that rotationally drives a photosensitive drum applied to an electrophotographic copying machine, a technique for restricting transmission of vibration to the photosensitive drum by interposing an anti-vibration rubber between gears is known. (For example, Patent Document 1).

  Further, a damping force variable damper device that exhibits a damping effect efficiently in a stepwise manner from a small earthquake to a large earthquake by operating a plurality of oil dampers in a stepwise manner is known (for example, Patent Document 2). .

  In addition, a multistage elasto-plastic damper that can exhibit energy absorption capability over a wide range of loads by yielding a plurality of plastic dampers having different yield strengths in stages is also known (for example, patents). Reference 3).

JP 2002-174932 A JP 2002-310227 A Japanese Patent Laid-Open No. 06-129465

  Here, in the image forming apparatus of Patent Document 1, as described above, the elastic deformation of the anti-vibration rubber is used to absorb the vibration and prevent the vibration from being transmitted to the photosensitive drum. ing.

  However, if the elastic modulus of the anti-vibration rubber changes over time according to the period of use or changes according to changes in the ambient temperature, the value of the deformation amount of the anti-vibration rubber changes depending on the use period and the ambient temperature. . As a result, it is not possible to satisfactorily prevent vibrations from being transmitted to the photosensitive drum, and a problem of periodic unevenness occurs in the image transferred to the recording material.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rotary damper capable of efficiently suppressing vibration transmission and an image forming apparatus having the rotary damper.

  In order to solve the above-mentioned problems, the invention of claim 1 is a rotary damper for transmitting a rotational force applied from a driving source to a first rotary body, wherein (a) A plurality of vibration suppressing portions for suppressing fluctuations in the rotation speed of the first rotating body; (b) an installation portion provided with the plurality of vibration suppression portions; and (c) about the peristaltic shaft. A focus suppressing portion that deforms at least one of the plurality of vibration suppression portions by relatively swinging, and the attention suppression portion that is at least one of the plurality of swinging portions is formed of a first viscoelastic body. A first deforming portion formed by the second viscoelastic body and a second deforming portion having a smaller elastic coefficient than the first deforming portion, and the rotating damper has a predetermined range with respect to the first rotating body. When transmitting the use drive torque in the first, the bullet of the first deformed portion over time As the coefficient changes, the state in which only the first deformation portion is compressed and deformed changes to the state in which the first deformation portion and the second deformation portion are compressively deformed, or the first deformation portion and the second deformation portion. It is characterized in that the state changes from the state in which only the first deformation part is compressed and deformed to the state in which only the first deformation part is compressed and deformed.

  According to a second aspect of the present invention, in the rotary damper according to the first aspect, the first viscoelastic body is made of a material whose elastic coefficient decreases with time, and the elastic coefficient of the first deformable portion is By decreasing with time, the state in which only the first deformable portion is compressed and deformed changes to the state in which the first deformable portion and the second deformable portion are compressively deformed, or the first viscoelastic body changes over time. The elastic modulus of the first deformable portion increases with time, and the first deformable portion and the second deformable portion are compressed and deformed by increasing the elastic modulus of the first deformable portion over time. Only one deformable portion changes to a state of compressive deformation.

  According to a third aspect of the present invention, in the rotary damper according to the first or second aspect, the elastic coefficient of the second deformable portion is such that only the first deformable portion is compressed and deformed, and the first deformable portion and the When the second deforming part changes to a state of compressive deformation, or when the first deforming part and the second deforming part change to a state where only the first deforming part is compressed and deformed, the first deforming part and the second deforming part change. One deformation portion is set to be approximately equal to the amount of change in elastic modulus that has changed over time.

  According to a fourth aspect of the present invention, there is provided a rotary damper for transmitting a rotational force applied from a driving source to the first rotary body, wherein (a) each of the first rotary body is rotated by being deformed. A plurality of vibration suppressing portions for suppressing speed fluctuations; (b) an installation portion provided with the plurality of vibration suppression portions; and (c) peristating relative to the installation portion about a peristaltic axis. And a focus suppressing portion that deforms at least one of the plurality of vibration suppression portions, and the focus suppression portion that is at least one of the plurality of swing portions is a first deformation portion formed of a first viscoelastic body. And a second deforming portion formed by a second viscoelastic body and having an elastic coefficient smaller than that of the first deforming portion, and the rotary damper applies a driving torque within a predetermined range to the first rotating body. When transmitting, to the change in the elastic modulus of the first deformation part due to temperature change There is no change in the state in which only the first deformable portion is compressed and deformed, and the first deformable portion and the second deformable portion are compressed and deformed, or the first and second deformable portions are compressed and deformed It is characterized in that only the first deforming portion is changed to a compressive deformation state.

  According to a fifth aspect of the present invention, in the rotary damper according to the fourth aspect, the first viscoelastic body is made of a material whose elastic coefficient decreases as the temperature rises, and the use of the rotary damper At the lower limit temperature TP0, only the first deformable portion is compressively deformed, and the elastic modulus of the first deformable portion decreases as the temperature rises, so that the first deformable portion and the second deformable portion are compressed at the temperature TP1. The elastic coefficient of the second deformable portion at the temperature TP1 is set to be approximately equal to the change amount of the elastic coefficient that the first deformable portion has changed from the temperature TP0 to the temperature TP1. It is characterized by.

  According to a sixth aspect of the present invention, in the rotary damper according to the fourth aspect, the first viscoelastic body is made of a material whose elastic coefficient increases as the temperature rises, and the use of the rotary damper At the lower limit temperature TP0, the first deformable portion and the second deformable portion are compressively deformed, and the elastic modulus of the first deformable portion increases as the temperature rises, so that only the first deformable portion is compressively deformed at the temperature TP1. The elastic coefficient of the second deformable portion at the temperature TP1 is set to be approximately equal to the amount of change in the elastic coefficient that the first deformable portion has changed from the temperature TP0 to the temperature TP1. It is characterized by.

  The invention according to claim 7 is the rotary damper according to any one of claims 1 to 6, wherein the length of the first deformation portion in the compression direction is greater than the length of the second deformation portion. Features.

  The invention according to claim 8 is the rotary damper according to any one of claims 1 to 7, wherein a pair of contact portions for compressively deforming the first viscoelastic body is provided on both sides of the first deformable portion. Is disposed on both sides of the second deformable portion, and a pair of contact portions for compressively deforming the second viscoelastic body is disposed, and the pair of contact portions of the first deformable portion and the second deformable portion The pair of contact portions are configured to have different angles with respect to the peristaltic axis, and have the same radius and the same phase.

  The invention according to claim 9 is a rotary damper for transmitting the rotational force applied from the drive source to the first rotary body, wherein (a) each of the first rotary body is rotated by being deformed. A plurality of vibration suppressing portions for suppressing speed fluctuations, (b) an installation portion provided with the plurality of vibration absorbing portions, and (c) peristating relative to the installation portion around a peristaltic axis. And a focus suppression unit that deforms at least one of the plurality of vibration suppression units, and the target suppression unit that is at least one of the plurality of vibration suppression units includes (a-1) one or more viscoelastic bodies (A-2) a pair of contact portions that are arranged on both sides of the deformation portion in the compression direction and apply pressure to the viscoelastic body, and the rotational force Is applied to the deformable portion from the pair of contact portions, and the rotary damper is Even when the elastic modulus of the deforming portion changes when transmitting the use driving torque within a predetermined range to the first rotating body, the contact cross-sectional area of the deforming portion with the pair of contact portions is By changing, the elastic modulus of the vibration suppressing portion is maintained to be equal.

  According to a tenth aspect of the present invention, in the rotary damper according to the ninth aspect, an elastic coefficient of the deformable portion distorted by the rotational force changes over time.

  According to an eleventh aspect of the present invention, in the rotary damper according to the ninth or tenth aspect, an elastic coefficient of the deformable portion that is distorted by the rotational force changes according to a temperature change.

  A twelfth aspect of the present invention is an image forming apparatus for forming an image on a recording material, which is described in any one of the first to eleventh aspects and transmits a rotational force applied from the driving source. And a photosensitive drum rotating portion which is provided as the first rotating body and rotates by a rotational force transmitted from the rotating damper.

In the invention according to any one of claims 1 to 12, when the rotary damper transmits the use driving torque within a predetermined range to the first rotating body, the rotary damper is changed over time or due to a temperature change.
(1) From a state in which only the first deforming portion is compressively deformed to a state in which the first deforming portion and the second deforming portion are compressively deformed, or
(2) From the state in which the first deforming portion and the second deforming portion are compressively deformed to the state in which only the first deforming portion is compressively deformed,
Change. Thereby, when it uses for a long time on the conditions of the same torque, the elastic coefficient as the whole rotation damper can be maintained in a desired range by the number and shape of the viscoelastic body which carries out compression deformation differing. Therefore, the rotational speed fluctuation | variation of a 1st rotary body can be suppressed, and the fluctuation range of the rotational speed of a 1st rotary body can be suppressed.

It is a front view showing an example of the whole composition of the image forming device in the 1st to 3rd embodiments of the present invention. It is a skeleton figure of the power transmission system in the drive part in the 1st and 3rd embodiment of this invention. It is a front perspective view which shows an example of a structure of the rotation damper in 1st and 3rd embodiment. It is a top view which shows an example of a structure of the rotation damper in 1st and 3rd embodiment. It is a front view which shows an example of a structure of the rotation damper in 1st and 3rd embodiment. It is a front view which shows an example of a structure of the rotation damper in 1st and 3rd embodiment. It is a front view for demonstrating operation | movement of the rotation damper in 1st and 3rd embodiment. It is a front view for demonstrating operation | movement of the rotation damper in 1st and 3rd embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 1st Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 1st Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 1st Embodiment. It is a graph which shows an example of a time-dependent change of the elastic modulus in a 1st embodiment. It is a skeleton figure of the power transmission system in the drive part in a 2nd embodiment. It is a front view which shows an example of a structure of the rotation damper in 2nd Embodiment. It is a front view which shows an example of a structure of the rotation damper in 2nd Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 2nd Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 2nd Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 2nd Embodiment. It is a graph which shows an example of a time-dependent change of the elastic modulus in a 2nd embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 3rd Embodiment. It is a front view which shows an example of a structure of the vibration suppression part in 3rd Embodiment. It is a graph which shows an example of the temperature change of an elastic modulus. It is a front view which shows the modification of the vibration suppression part in 3rd Embodiment. It is a front view which shows the modification of the vibration suppression part in 3rd Embodiment. It is a front view which shows the modification of the vibration suppression part in 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<1. First Embodiment>
<1.1. Configuration of image forming apparatus>
FIG. 1 is a front view showing an example of the overall configuration of the image forming apparatus 1 according to the first embodiment of the present invention. Here, the image forming apparatus 1 prints a monochrome image or a color image by an electrophotographic method. The image forming apparatus 1 can be incorporated into a multi-function machine having a copy function, a print function, a facsimile function, and the like. As shown in FIG. 1, the image forming apparatus 1 mainly includes a printer unit 10, a paper feed unit 30, a fixing unit 40, a paper discharge unit 50, a scanner unit 55, a display unit 80, and a control unit 90. And.

  In FIG. 1 and the subsequent drawings, an XYZ orthogonal coordinate system in which the Z-axis direction is a vertical direction and the XY plane is a horizontal plane is appropriately attached as necessary to clarify the directional relationship. .

  The printer unit 10 prints a monochrome image or a color image on the recording material P supplied via the paper feed path R1 and the transport path Ra. As shown in FIG. 1, the printer unit 10 mainly includes an image forming unit 11 (11Y, 11M, 11C, and 11K), an exposure scanning unit 20 (20Y, 20M, 20C, and 20K), an intermediate transfer belt 21, and the like. have.

  A plurality (four in the present embodiment) of image forming units 11 correspond to yellow (Y), magenta (M), cyan (C), and black (K), respectively. As shown in FIG. 1, each image forming unit 11 (11Y, 11M, 11C, 11K) mainly includes a photosensitive drum 13 (13Y, 13M, 13C, 13K) and a charging charger 14 (14Y, 14M, 14C, 14K), developing unit 16 (16Y, 16M, 16C, 16K), primary transfer roller 18 (18Y, 18M, 18C, 18K), drum cleaner 19 (19Y, 19M, 19C, 19K), and exposure scanning unit 20 (20Y, 20M, 20C, 20K).

  Here, a so-called tandem system is adopted as the printer unit 10 of the present embodiment, and each image forming unit 11 (11Y, 11M, 11C, 11K) is, for example, from the left side of the page as shown in FIG. To the right, yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the intermediate transfer belt 21 in this order. Each image forming unit 11 (11Y, 11M, 11C, 11K) is disposed below the intermediate transfer belt 21.

  In the present embodiment, the image forming units 11Y, 11M, 11C, and 11K have the same type of hardware configuration. Therefore, in the following, the image forming unit 11Y and the photosensitive drum 13Y, the charging charger 14Y, the developing unit 16Y, the primary transfer roller 18Y, the drum cleaner 19Y, and the exposure scanning unit 20Y, which are the components of the image forming unit 11Y, are described in detail. Explained.

  For convenience of illustration, the photosensitive drums 13M, 13C, and 13K, the chargers 14M, 14C, and 14K, the developing units 16M, 16C, and 16K, the primary transfer rollers 18M, 18C, and 18K, and the drum cleaners 19M, 19C, and 19K. Each reference numeral is omitted in FIG. 1 and subsequent figures.

  The photosensitive drum 13Y has a cylindrical shape or a columnar shape, and is disposed on the opposite side of the primary transfer roller 18Y with the intermediate transfer belt 21 interposed therebetween. A photoconductive film is provided on the outer peripheral surface of the photosensitive drum 13Y.

  Therefore, light is irradiated from the corresponding exposure scanning unit 20Y to the outer peripheral surface of the photosensitive drum 13Y, and the charge on the irradiated portion is removed, so that the outer peripheral surface of the photosensitive drum 13Y has a static corresponding to yellow (Y). An electrostatic latent image is formed. Similarly, electrostatic latent images corresponding to magenta, cyan, and black are formed on the outer peripheral surfaces of the photosensitive drums 13M, 13C, and 13K, respectively.

  The charging charger 14Y applies an electric charge to the outer peripheral surface of the photosensitive drum 13Y by being in contact with the outer peripheral surface of the photosensitive drum 13Y. The developing unit 16Y forms a toner image based on the electrostatic latent image on the outer peripheral surface of the photosensitive drum 13Y by supplying yellow (Y) toner to the photosensitive drum 13Y on which the electrostatic latent image is formed. .

  As shown in FIG. 1, the primary transfer roller 18Y is disposed on the opposite side of the photosensitive drum 13Y with the intermediate transfer belt 21 interposed therebetween. The primary transfer roller 18Y is given a charge having a polarity opposite to that of the outer peripheral surface of the photosensitive drum 13Y. Thus, when the intermediate transfer belt 21 is sandwiched between the photosensitive drum 13Y and the primary transfer roller 18Y while the photosensitive drum 13Y and the primary transfer roller 18Y rotate, a yellow (Y) toner image is formed on the intermediate transfer belt 21. Is transcribed.

  The drum cleaner 19Y transfers the toner remaining on the photosensitive drum 13Y to the outer periphery of the photosensitive drum 13Y in a period before the next yellow toner is supplied from the developing unit 16Y after the toner image is transferred to the intermediate transfer belt 21. Remove from the surface. As shown in FIG. 1, the drum cleaner 19Y is provided at a position where it can come into contact with the outer peripheral surface of the photosensitive drum 13Y.

  The exposure scanning unit 20 (20Y, 20M, 20C, 20K) is a so-called exposure unit, and irradiates the corresponding photosensitive drum 13 (13Y, 13M, 13C, 13K) with laser light. Thereby, an electrostatic latent image is formed on the outer peripheral surface of the corresponding photosensitive drum 13 (13Y, 13M, 13C, 13K).

  The intermediate transfer belt 21 transfers the four-color toner images primarily transferred by the image forming units 11 (11Y, 11M, 11C, and 11K) to the recording material P. As shown in FIG. 1, the intermediate transfer belt 21 is wound around a driving roller 22 and a driven roller 23, and the driving roller 22 and the driven roller 23 rotate counterclockwise in FIG. Further, the secondary transfer roller 25 is disposed on the opposite side of the driving roller 22 across the transport path Ra, and contacts the outer periphery of the intermediate transfer belt 21.

  Accordingly, the four-color toner images formed on the outer periphery of the intermediate transfer belt 21 are recorded by adjusting the feed timing of the intermediate transfer belt 21 and the conveyance timing of the recording material P conveyed on the conveyance path Ra. Secondary transfer is performed on the material P.

  The developer supplied from the developing unit 16 of each image forming unit 11 is preferably a one-component developer that does not use a carrier, but may be a two-component developer that includes a toner and a carrier. Further, as the material of the intermediate transfer belt 21, polycarbonate, polyimide, polyamideimide, or the like can be used.

  The temperature / humidity sensor 29 is a detection unit that detects the temperature and / or humidity near the printer unit 10. The voltage applied to the primary transfer roller 18 (18Y, 18M, 18C, 18K) and the secondary transfer roller 25 is adjusted based on the temperature and humidity detected by the temperature / humidity sensor 29.

  Here, the primary and secondary transfer rollers 18 and 25 are so-called elastic rollers, and are formed of, for example, a synthetic rubber such as nitrile rubber added with an ion conductive material and foamed.

  The paper feed unit 30 is used as a supply unit that supplies the recording material P to the printer unit 10. As shown in FIG. 1, the paper feed unit 30 mainly includes a paper feed cassette 31 and a paper feed roller 32.

  The paper feed cassette 31 is a storage unit that can store a plurality of recording materials P. The paper feed roller 32 feeds a plurality of recording materials P accommodated in the paper feed cassette 31 in order from the uppermost layer and supplies the fed recording materials P to the paper feed path R1.

  The registration roller 33 controls the timing at which the recording material P is sent out to the transport path Ra. Here, when the “direction in which the recording material P is conveyed” is defined as the “conveyance direction”, the registration roller 33 is provided on the downstream side of the paper feed roller 32 in the conveyance direction, as shown in FIG. Yes.

  The sheet detection sensor 35 is a detection unit that detects the leading edge of the recording material P. As shown in FIG. 1, the sheet detection sensor 35 is provided on the downstream side of the registration roller 33 in the transport direction. When the leading edge of the recording material P reaches the sheet detection sensor 35, the output from the sheet detection sensor 35 transitions from an off state to an on state, for example. Therefore, by monitoring the output value output from the sheet detection sensor 35, it can be determined whether or not the recording material P has been fed just before the registration roller 33.

  The fixing unit 40 fixes the toner image transferred onto the recording material P. As shown in FIG. 1, the fixing unit 40 is disposed on the downstream side of the secondary transfer roller 25 in the path along the transport path Ra.

  The paper discharge unit 50 is provided on the downstream side of the fixing unit 40 in the transport direction, and discharges the recording material P on which the toner image is fixed to the outside of the apparatus. That is, the recording material P supplied to the paper discharge unit 50 via the transport path Ra is guided to the paper discharge path R2. As shown in FIG. 1, the paper discharge unit 50 mainly includes a paper discharge roller pair 51 provided on the paper discharge path R <b> 2 and a paper discharge tray 52.

  The scanner unit 55 reads an image from an original by an automatic document feeder (ADF) method or a flat bed method. As shown in FIG. 1, the scanner unit 55 is disposed above the paper discharge unit 50.

  The display unit 80 is configured by a liquid crystal display, for example, and has a function as a “touch panel” that can specify a position on the screen by touching the screen with a finger or a dedicated pen. Therefore, a user of the image forming apparatus 1 (hereinafter simply referred to as “user”) gives an instruction using the “touch panel” function of the display unit 80 based on the content displayed on the display unit 80. The image forming apparatus 1 can execute a predetermined process (for example, a process of printing a toner image on the recording material P supplied from the paper feeding unit 30). Thus, the display unit 80 can be used as a receiving unit that receives an input operation from the user.

  The operation unit 85 is an input unit configured by a plurality of keypads. For example, when the print start button 86 included in the operation unit 85 is pressed, a printing process is performed on the recording material P. In this way, the operation unit 85 can be used as a reception unit that receives an input operation from the user, similarly to the display unit 80.

  As shown in FIG. 1, the control unit 90 is provided below the paper discharge tray 52. The control unit 90 realizes operation control of each element of the image forming apparatus 1 and data calculation. As shown in FIG. 1, the control unit 90 mainly includes a ROM 91, a RAM 92, an image memory 93, and a CPU 95.

  A ROM (Read Only Memory) 91 is a so-called nonvolatile storage unit, and stores, for example, a program 91a. As the ROM 91, a flash memory that is a readable / writable nonvolatile memory may be used.

  A RAM (Random Access Memory) 92 and an image memory 93 are volatile storage units. The RAM 92 stores, for example, data used in the calculation of the CPU 95. The image memory 93 stores image data corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K).

  A CPU (Central Processing Unit) 95 executes control according to the program 91a of the ROM 91, various data arithmetic processes, and the like. For example, the CPU 95 receives an image signal from an external terminal (not shown), converts it into digitized image data for YK colors, and controls the operations of the printer unit 10 and the sheet feeding unit 30. As a result, the printing process on the recording material P is executed.

<1.2. Configuration of drive unit>
FIG. 2 is a skeleton diagram of the power transmission system in the drive unit 60. Here, the driving unit 60 includes a photosensitive drum 13 (13Y, 13M, 13C, 13K) of each image forming unit 11 (11Y, 11M, 11C, 11K) and a developing unit 16 (16Y, 16M, 16C, 16K). (More specifically, a rotational force is applied to the developing roller 17 (17Y, 17M, 17C, 17K, etc.) of each developing unit 16). As shown in FIG. 2, the drive unit 60 mainly includes a motor 61 and a plurality of drive gears 62, 63, 65, 66, 68 and 69.

  For convenience of illustration, FIG. 2 shows that the photosensitive drums 13M and 13Y out of the plurality of photosensitive drums 13 (13Y, 13M, 13C, and 13K) have a plurality of developing units 16 (16Y, 16M, 16C, and 16K). ), The developing section 16Y is the developing roller 17Y (17Y, 17M, 17C, 17K), and the developing roller 17Y is the rotating damper 70Y, 70M, of the plurality of rotating dampers 70 (70Y, 70M, 70C, 70K). Are described respectively.

  In the following description, the image forming units 11Y to 11K, the photosensitive drums 13Y to 13K, the developing units 16Y to 16K, the developing rollers 17Y to 17K, and the rotary dampers 70Y to 70K are collectively referred to as the image forming unit 11, It is also called a photosensitive drum 13, a developing unit 16, a developing roller 17, and a rotary damper 70.

  As shown in FIG. 2, the drive gear 62 is attached to the shaft center of the motor 61. Further, the input side of the first relay gear 63 is engaged with the drive gear 62. Further, the output side of the first relay gear 63 is meshed with each of the input gears 65 (65Y, 65M).

  As shown in FIG. 2, the input gear 65Y, the output gear 66Y, and the rotary damper 70Y are attached to the shaft center of the photosensitive drum 13Y. Further, the docking gear 69 is attached to, for example, the axis of the developing roller 17Y of the developing unit 16Y. Further, the input side of the second relay gear 68 is meshed with the output gear 66Y, and the output side of the second relay gear 68 is meshed with the docking gear 69.

  Therefore, the photosensitive drum 13Y (photosensitive member rotating unit) is rotated by the rotational force transmitted from the rotary damper 70Y. Further, the developing roller 17Y (developing rotating unit) is rotated by the rotational force transmitted through the rotating damper 70Y, the second relay gear 68, and the docking gear 69. That is, the rotational force of the motor 61 is branched by a photoreceptor driving system (for example, the output gear 66Y provided at the axis of the photoreceptor drum 13Y). The branched rotational force is transmitted to the developing roller 17Y.

  Similarly, as shown in FIG. 2, the input gear 65M, the output gear 66M, and the rotary damper 70M are attached to the shaft center of the photosensitive drum 13M. Accordingly, the rotary damper 70M is rotated by the rotational force transmitted through the drive gear 62, the first relay gear 63, the input gear 65, and the rotary damper 70.

<1.3. Configuration of rotating damper>
3 and 4 are a front perspective view and a plan view showing an example of the configuration of the rotary damper 70, respectively. Each of FIGS. 5 and 6 is a front view showing an example of the configuration of the rotary damper 70. 7 and 8 are front views for explaining the operation of the rotary damper 70. FIG. Each of FIG. 9 to FIG. 11 is a front view showing an example of the configuration of the vibration suppressing unit 75a.

  Here, the rotary damper 70 transmits the driving force applied from the motor 61 (driving source) to the photosensitive drum 13 (first rotating body). As shown in FIGS. 3 to 6, the rotary damper 70 mainly includes an installation part 71, a peristaltic part 72, and a plurality of vibration suppressing parts 75 (75 a to 75 c).

  The installation part 71 is a disk-shaped board | plate material, as shown in FIG. One of the main surfaces of the installation part 71 is provided with a plurality of vibration suppression parts 75 (75a to 75c) and a columnar peristaltic shaft 71a. As shown in FIG. 5, the peristaltic part 72 is a disk-shaped plate material, and peristates about a peristaltic shaft 71a. Here, in the present embodiment, the “main surface” of the installation portion 71 refers to a plane having the swing axis 71a of the rotary damper 70 as a substantial normal vector.

  A plurality (three in the present embodiment) of vibration suppressing portions 75 (75a to 75c) are mounted on the installation portion 71. As shown in FIG. 5, each vibration suppression part 75 (75a-75c) is the same distance from the peristaltic shaft 71a, and the center angle is equiangular (120 degrees in this embodiment). Has been placed.

  Then, as shown in FIGS. 7 and 8, each vibration suppression unit 75 (75a to 75c) is deformed along the direction of the arrow AR1 (compression direction), so that the rotational speed fluctuation (that is, desired) of the photosensitive drum 13 is changed. The fluctuation of the rotational speed of the photosensitive drum 13 with respect to the speed) is suppressed. As shown in FIGS. 5, 6, and 9 to 11, the vibration suppressing portion 75 a mainly includes a pair of contact portions 76 (76 a, 76 b) and a plurality (three in this embodiment) of deformed portions. 77 (77a to 77c) and a plurality of pins 78 and 79.

  Here, each vibration suppression part 75a-75c of this Embodiment has the same hardware constitutions. Therefore, in the following, attention is paid to the vibration suppression unit 75a, and the vibration suppression unit 75a as the focus suppression unit will be described.

  In the following description, the vibration suppression portions 75a to 75c are collectively referred to as the vibration suppression portion 75, and the deformation portions 77a to 77c are also collectively referred to as the deformation portion 77.

  A pair of contact part 76 (76a, 76b) is arrange | positioned at the both sides of the some deformation | transformation part 77 (77a-77c), as shown in FIGS. A plurality (three in the present embodiment) of the deforming portions 77 (77a to 77c) are formed of first, second, and third viscoelastic bodies, respectively. In addition, the elastic coefficients of the first to third viscoelastic bodies that are distorted by the rotational force change over time.

  Further, as shown in FIGS. 9 to 11, when no rotational force is applied, the length D of the deformed portion 77a in the compression direction is “D11”, and the deformed portion 77b (length D = “D12”). ) And the deformation portion 77c (length D = “D13”).

  The fixing pin 78 is a rod body that fixes the contact portion 76 a to the swinging portion 72. As shown in FIGS. 3 and 4, the fixing pin 78 is inserted into the through hole 78a of the contact portion 76a. One end of the fixing pin 78 is fixed to the peristaltic part 72.

  The transmission pin 79 is a rod body that transmits the rotational force applied to the rotary damper 70 from the motor 61 to the corresponding vibration suppression unit 75. As shown in FIGS. 3 and 4, the transmission pin 79 is inserted into the through hole 79a of the contact portion 76b. One end of the transmission pin 79 is fixed to the installation portion 71, and the other end of the transmission pin 79 is inserted into a guide hole 72 b formed in the swinging portion 72. Thereby, when a rotational force is applied to the rotary damper 70 and the input side installation portion 71 rotates, the transmission pin 79 of each vibration suppression portion 75 swings in the compression direction around the swing shaft 71a, thereby suppressing vibration. The part 75 is compressed and deformed (see FIGS. 7 and 8), and the rotational force is transmitted to the peristaltic part 72 on the output side.

  Here, in the present embodiment, the photosensitive drum 13 and the developing roller 17 of the developing unit 16 are rotated by a rotational force supplied from a single motor 61. In this case, for example, when the rotation of the developing roller 17 varies depending on the toner storage status, the vibration caused by the variation occurs as the variation in rotational force and / or rotational speed via the second relay gear 68 and the docking gear 69. , Transmitted to the rotary damper 70.

  However, the rotation damper 70 is provided with a plurality of vibration suppressing portions 75, and the vibration is absorbed by each vibration suppressing portion 75. As a result, no motor is provided for each of the photosensitive drum 13 and the developing roller 17, and even when the photosensitive drum 13 and the developing roller 17 are rotated by a single motor 61, the photosensitive drum 13. The rotation speed can be kept constant. Therefore, the image forming apparatus 1 according to the present embodiment can simultaneously satisfy the improvement in transfer performance and the reduction in the number of parts and the manufacturing cost.

  FIG. 12 is a graph showing an example of the change over time of the elastic coefficient in the vibration suppressing unit 75. The vertical axis in FIG. 12 represents the elastic coefficient E (Pa) of the viscoelastic body, and the horizontal axis represents the elapsed time T (day). The elastic modulus of the first viscoelastic body that forms the deformable portion 77a is the second viscoelastic body that forms the deformable portion 77b and the third viscoelastic body that forms the deformable portion 77c, as shown by a curve C11 (dashed line). The elastic modulus of each changes in accordance with the elapsed time used as shown by a curve C12 (two-dot chain line).

  That is, as shown in FIG. 12, the common points of the curves C11 and C12 are points that decrease as the elapsed time T increases and have the same inclination with respect to the horizontal axis (T axis). The difference between the curves C11 and C12 is that the intercept from the vertical axis (E axis) is different. Furthermore, as shown in FIG. 12, the elastic coefficient (second coefficient) of the second viscoelastic body forming the deformable portion 77a is greater than the elastic coefficient (first coefficient) of the first viscoelastic body forming the deformable portion 77b. Is also small.

  When a certain rotational force is applied to the vibration suppression unit 75 having the first to third viscoelastic bodies, the elastic coefficient of the entire vibration suppression unit 75 is represented by a curve CC1 (solid line) in FIG. To change.

  First, when the elapsed time T is in the range of “T10” (at the start of use) to “T11”, a constant rotational force within a predetermined range is applied to the vibration suppressing unit 75, and the photosensitive drum 13 is used and driven from the rotary damper 70 When torque is transmitted, the length D of the deformed portion 77a in the compression direction becomes “D12” or more and less than “D11” due to a change over time. Thereby, a pair of contact part 76 (76a, 76b) contacts only the deformation | transformation part 77a (refer FIG. 9). Therefore, in the range of the elapsed time T from “T10” to “T11”, the curve CC1 has the same shape as the curve C11, and the value of the elastic coefficient E of the entire vibration suppressing portion 75 is the elastic coefficient of the deforming portion 77a. As shown in FIG. 12, the value is between “E11” and “E12”. When the elapsed time T is in the range of “T10” to “T11”, the other deformed portions 77b and 77c are not loaded and do not deteriorate due to use, and therefore maintain the initial elastic modulus. ing. In the present embodiment, “use driving torque” refers to torque transmitted from the motor 61 (see FIG. 2) and transmitted to the photosensitive drum 13 via each vibration suppression unit 75.

  Next, when a certain rotational force is applied to the vibration suppressing portion 75 in the range of the elapsed time T from “T11” to “T12”, the length D of the deformable portion 77a in the compression direction is caused by the change over time due to use. It becomes "D13" or more and less than "D12". Thereby, a pair of contact part 76 (76a, 76b) contacts deformation | transformation part 77a, 77b (refer FIG. 10). Therefore, when the elapsed time T is in the range from “T11” to “T12”, the curve CC1 has a shape in which the curve C12 is superimposed on the curve C11, and the value of the elastic coefficient E of the entire vibration suppressing unit 75 is the same as that of the deformed portion 77a. The value obtained by adding the elastic coefficients of the portion 77b is a value between “E11” and “E12” as shown in FIG. Note that at the time of the elapsed time T11, the elastic coefficient of the deformed portion 77b is almost “E10” because it hardly changes with time. For this reason, when the deformation | transformation part 77b starts a contact in the elapsed time T11, the increase amount of the elastic coefficient (curve CC1) of the vibration suppression part 75 whole becomes E10. The value of the increase amount, that is, the elastic coefficient of the deforming portion 77b is set to be equal to the temporal change amount (E12-E11) until the elapsed time T11 of the entire vibration suppressing portion 75.

  That is, the elastic modulus (second coefficient) of the deformable portion 77b when the deformable portions 77a and 77b are changed to the state of compressive deformation is the elastic coefficient of the elastic modulus (first coefficient) of the deformable portion 77a that has changed over time. Is set approximately equal to the amount of change.

  Subsequently, when a certain rotational force is applied to the vibration suppressing portion 75 in the range after the elapsed time T is “T12”, the length D of the deformable portions 77a and 77b in the compression direction is “D13” due to a change with time. It becomes as follows. Thereby, a pair of contact part 76 (76a, 76b) contacts deformation | transformation part 77a, 77b, 77c (refer FIG. 11). Therefore, in the range after the elapsed time T is “T12”, the curve CC1 has a shape in which the two curves C12 are superimposed on the curve C11. Similarly, the amount of increase in the elastic coefficient (curve CC1) of the entire vibration suppressing portion 75 at the elapsed time T12 is also the value “E10” of the elastic modulus of the deforming portion 77c. At the time point of the elapsed time T12, the value of the elastic coefficient E of the entire vibration suppressing unit 75 is close to the initial elastic coefficient (elapsed time zero) value “E12”, and a considerable time from the elapsed time T12 is “E11”. And a value between “E12” can be maintained.

  Thus, the elastic modulus E of each deformation | transformation part 77 (77a-77c) reduces with the time passage accompanying use. Moreover, the length D of each deformation | transformation part 77 (77a-77c) differs, respectively. As a result, as shown in FIGS. 9 to 12, the number and state of the deforming portions 77 (77 a to 77 c) acting according to the elapsed time T change. Therefore, even if the elastic modulus E of each deformation part 77 (77a-77c) changes with time, the elastic coefficient E of the vibration suppression part 75 as a whole falls within the desired range (E11-E12).

  In the present embodiment, the physical properties of the second and third viscoelastic bodies (for example, the elastic coefficient when not in use and the rate of change of the elastic coefficient per unit time when used) are the same. However, the present invention is not limited to this. For example, the second and third viscoelastic bodies may have different material properties as long as the elastic modulus E of the entire vibration suppressing portion 75 can be within a desired range (E11 to E12).

  In addition, the elastic coefficient of each viscoelastic body is preferably in the range of 1 MPa to 22 MPa (Pa). The viscosity of each elastic body is preferably in the range of 5.0E−2 to 1.0E + 2 (0.05 to 100) (Pa · s).

<1.4. Advantages of Rotary Damper of First Embodiment>
As described above, when the rotary damper 70 transmits the use driving torque within a predetermined range to the photosensitive drum 13, the deformations 77a and 77b are changed from the state in which only the deformation part 77a is compressed and deformed by changing with time. Changes to a state of compressive deformation. Further, by further changing over time, the rotary damper 70 changes from a state where the deformable portions 77a, 77b are compressed and deformed to a state where the deformable portions 77a, 77b, 77c are compressed and deformed. As a result, when used for a long time under the same torque conditions (usable drive torque within a predetermined range), the number and shape of the viscoelastic bodies to be compressed and deformed differ, so that the elastic coefficient of the rotary damper 70 as a whole is desired. Can be kept within range. Therefore, fluctuations in the rotational speed of the photosensitive drum 13 can be suppressed, and fluctuations in the rotational speed of the photosensitive drum 13 can be suppressed.

  As a result, the vibration of the developing roller 17 can be prevented from being transmitted to the photosensitive drum 13, and the periodic unevenness of the image transferred from the photosensitive drum 13 to the recording material P cannot be recognized by the user of the image forming apparatus 1. Can be reduced to a certain extent.

  Further, since the rotary damper 70 can reduce vibration as described above, the image forming apparatus 1 can be prevented from being damaged due to vibration.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described. The image forming apparatuses 1 and 100 of the first and second embodiments have the same configuration except that the configurations of the corresponding rotary dampers 70 and 170 are different. Therefore, in the following, this difference will be mainly described.

  It should be noted that the same constituent elements in the image forming apparatuses 1 and 100 are denoted by the same reference numerals, and the constituent elements having the same reference numerals have been described in the first embodiment. Therefore, description is abbreviate | omitted in this Embodiment.

<2.1. Configuration of drive unit and rotary damper>
FIG. 13 is a skeleton diagram of the power transmission system in the drive unit 160. Each of FIG. 14 and FIG. 15 is a front view showing an example of the configuration of the rotary damper 70. Each of FIGS. 16 to 18 is a front view illustrating an example of the configuration of the vibration suppressing unit 175a.

  Similarly to the driving unit 60 of the first embodiment, the driving unit 160 includes the photosensitive drum 13 of each image forming unit 11 and the developing unit 16 (more specifically, the developing roller 17 of each developing unit 16 and the like). ) Is given a rotational force. As shown in FIG. 13, the drive unit 160 is obtained by replacing the rotary damper 70 (70Y, 70M, 70C, 70K) of FIG. 2 with a corresponding rotary damper 170 (170Y, 170M, 170C, 170K).

  For convenience of illustration, FIG. 13 shows the rotary dampers 170Y and 170M among the plurality of rotary dampers 170 (170Y, 170M, 170C, and 170K). In the following description, the rotary dampers 170Y to 170K are also collectively referred to as a rotary damper 170.

  The rotary damper 170 transmits the rotational force applied from the motor 61 to the photosensitive drum 13, similarly to the rotary damper 70 of the first embodiment. As shown in FIGS. 14 and 15, the rotary damper 170 mainly has an installation part 71, a peristaltic part 72, and a plurality of vibration suppression parts 175 (175 a to 175 d).

  A plurality (four in the present embodiment) of vibration suppression units 175 (175a to 175d) are mounted on the installation unit 71. As shown in FIG. 14, each vibration suppression unit 175 (175a to 175d) has a similar distance from the peristaltic shaft 71a, and the center angle is equiangular (90 degrees in the present embodiment). Has been placed.

  And each vibration suppression part 175 (175a-175d) deform | transforms along arrow AR1 direction (refer FIG. 16 grade | etc.,), And the rotational speed fluctuation | variation of the photosensitive drum 13 is suppressed.

  As shown in FIGS. 16 and 18, the vibration suppressing portion 175a (first suppressing portion) mainly includes a pair of contact portions 76 (76a, 76b), a plurality of pins 78, 79, and a deforming portion 177a. Have. As shown in FIG. 17, the vibration suppressing portion 175b (second suppressing portion) mainly includes a pair of contact portions 76 (76a, 76b), a plurality of pins 78, 79, and a deforming portion 177b. doing.

  A pair of contact part 76 (76a, 76b) is arrange | positioned at the both sides of the deformation | transformation part 177 (177a-177d), as shown in FIG.14, FIG.16 and FIG.17. The pair of contact portions 76 corresponding to the respective deformation portions 177 are configured to have the same radius and different angles with respect to the swing shaft 71a.

  Here, the deformation portion 177a included in the vibration suppression portion 175a is formed by the first viscoelastic body, and the deformation portion 177b included in the vibration suppression portion 175b is formed by the second viscoelastic body. The elastic coefficient of each viscoelastic body is preferably in the range of 1 MPa to 22 MPa (Pa), as in the case of the first embodiment. The viscosity of each elastic body is preferably in the range of 5.0E−2 to 1.0E + 2 (0.05 to 100) (Pa · s).

  Furthermore, each vibration suppression unit 175c of the present embodiment has the same hardware configuration as the vibration suppression unit 175a, and the vibration suppression unit 175d has the same hardware configuration as the vibration suppression unit 175b. Therefore, hereinafter, the vibration suppression units 175a and 175b will be described. Hereinafter, the vibration suppression units 175a to 175d are collectively referred to as a vibration suppression unit 175.

  Here, in the present embodiment, the photosensitive drum 13 and the developing roller 17 of the developing unit 16 are rotated by a rotational force supplied from a single motor 61 as in the first embodiment. In this case, for example, when the rotation of the developing roller 17 varies depending on the toner storage status, the vibration caused by the variation occurs as the variation in rotational force and / or rotational speed via the second relay gear 68 and the docking gear 69. And transmitted to the rotary damper 170.

  However, the rotation damper 170 is provided with a plurality of vibration suppressing portions 175, and the vibration is absorbed by each vibration suppressing portion 175. As a result, no motor is provided for each of the photosensitive drum 13 and the developing roller 17, and even when the photosensitive drum 13 and the developing roller 17 are rotated by a single motor 61, the photosensitive drum 13. The rotation speed can be kept constant. Therefore, like the image forming apparatus 1 of the first embodiment, the image forming apparatus 100 of the present embodiment can simultaneously satisfy the improvement in transfer performance and the reduction in the number of parts and the manufacturing cost. Become.

  FIG. 19 is a graph showing an example of the change over time of the elastic modulus in the rotary damper 170. In FIG. 19, the vertical axis represents the elastic coefficient E (Pa) of the entire rotary damper 170, and the horizontal axis represents the elapsed time T (day). In addition, the elastic coefficient corresponding to the vibration suppression units 175a and 175c is used as a curve C21 (one-dot chain line), and the elastic coefficient corresponding to the vibration suppression units 175b and 175d is used as a curve C22 (two-dot chain line). It changes depending on the elapsed time.

  That is, as shown in FIG. 19, the common points of the curves C21 and C22 are points that decrease as the elapsed time T increases and have the same inclination with respect to the horizontal axis (T axis). The difference between the curves C21 and C22 is that the intercept from the vertical axis (E axis) is different.

  When a certain rotational force is applied to the rotary damper 170 having such vibration suppressing portions 175 (175a to 175d), the elastic coefficient of the entire rotary damper 170 is as shown by a curve CC2 (solid line) in FIG. To change.

  First, when a certain rotational force within a predetermined range is applied to the rotary damper 170 in the range of the elapsed time T from “T20” (at the start of use) to “T21”, the length D of the deformed portion 177a in the compression direction. Becomes “D22” or more and less than “D21” due to the change over time. Thereby, a pair of contact part 76 (76a, 76b) contacts only the deformation | transformation part 177a (refer FIG. 16 and FIG. 17). Therefore, in the range of elapsed time T from “T20” to “T21”, the curve CC2 has the same shape as the curve C21, and the value of the elastic coefficient E of the entire rotary damper 170 is “E21” as shown in FIG. ”To“ E22 ”. When the elapsed time T is in the range from “T20” to “T21”, the deformed portion 177b is not loaded and does not deteriorate due to use, and therefore maintains the initial elastic modulus.

In addition, when viewed from the intersection of the installation portion 71 and the swing shaft 71a,
(1) An angle (phase difference) formed by the contact portion 76a of the vibration suppressing portion 175a and the contact portion 76a of the vibration suppressing portion 175b,
(2) an angle (phase difference) formed by the contact portion 76b of the vibration suppressing portion 175a and the contact portion 76b of the vibration suppressing portion 175b;
Is a similar value. That is, the pair of contact portions 76 corresponding to the deformation portion 177a and the pair of contact portions 76 corresponding to the deformation portion 177b have the same phase.

  Next, in the range of the elapsed time T from “T21” to “T22”, when a constant rotational force is applied to the rotary damper 170, the length D of the deformed portions 177a and 177b in the compression direction is less than “D22”. Become. Thereby, a pair of contact part 76 (76a, 76b) contained in each vibration suppression part 175a, 175b contacts with corresponding deformation | transformation part 177a, 177b, respectively (refer FIG. 17 and FIG. 18). Therefore, in the range of the elapsed time T from “T21” to “T22”, the curve CC2 has a shape in which the curve C21 is superimposed on the curve C21, and the value of the elastic coefficient E of the entire rotary damper 170 is the vibration suppression portion 175a, This is a value obtained by adding the elastic coefficient of 175b, and is a value between “E21” and “E22” as shown in FIG. Note that, at the time of the elapsed time T11, the elastic coefficient of the vibration suppressing unit 175b is the initial “E20” because it hardly changes over time. For this reason, when the vibration suppression unit 175b starts to contact at the elapsed time T21, the increase amount of the elastic coefficient (curve CC2) of the entire rotary damper 170 becomes E20. The value of the increase amount, that is, the elastic coefficient of the vibration suppressing unit 175b is set to be equal to the amount of change with time (E22-E21) until the elapsed time T21 of the entire rotary damper 170.

  Thus, the elastic modulus E of each vibration suppression part 175a-175d contained in the rotation damper 170 decreases with the passage of time with use. In addition, regarding the length D of each of the vibration suppression units 175a to 175d before the start of rotation, the value of the length D of the vibration suppression units 175a and 175c is “D21”, and the length of the vibration suppression units 175b and 175d. The value of the length D is “D22” (<“D21”).

  Thereby, as shown in FIGS. 16-19, the number and state of the vibration suppression part 175 (175a-175d) which act according to the elapsed time T change. Therefore, even when the elastic coefficient E of each 175 (175a to 175d) changes with time, the elastic coefficient E of the entire rotary damper 170 falls within the desired range (E21 to E22).

In the case where the elapsed time T is in the range from “T21” to “T22”, as in the case where the elapsed time T is in the range from “T20” to “T21”,
(1) The phase difference between the contact portion 76a of the vibration suppressing portion 175a and the contact portion 76a of the vibration suppressing portion 175b,
(2) the phase difference between the contact portion 76b of the vibration suppressing portion 175a and the contact portion 76b of the vibration suppressing portion 175b;
Is a similar value. That is, the pair of contact portions 76 corresponding to the deformation portion 177a and the pair of contact portions 76 corresponding to the deformation portion 177b have the same phase.

  In addition, the first and second viscoelastic bodies may be formed of the same type of material as long as the fluctuation of the rotation speed of the photosensitive drum 13 described above can be suppressed, and the vibration suppression units 175a to 175d are respectively You may form by the viscoelastic material of a different material.

<2.2. Advantages of Rotary Damper of Second Embodiment>
As described above, in the rotary damper 170 of the present embodiment, the pair of contact portions 76 of the deformation portion 177a and the pair of contact portions 76 of the deformation portion 177b are at different angles with respect to the swing shaft 71a, and , The same radius and the same phase. Thereby, when it uses for a long time on the conditions of the same torque, the elastic coefficient as the whole rotation damper 170 can be maintained in a desired range by the number and shape of the viscoelastic body which carries out compression deformation differing. Therefore, fluctuations in the rotational speed of the photosensitive drum 13 can be suppressed, and fluctuations in the rotational speed of the photosensitive drum 13 can be suppressed.

<3. Third Embodiment>
Next, a third embodiment of the present invention will be described. The image forming apparatuses 1 and 200 according to the first and third embodiments have the same configuration except that the configurations of the corresponding vibration suppression units 75 and 275 are different. Therefore, in the following, this difference will be mainly described.

  Note that the same components in the image forming apparatuses 1 and 200 are denoted by the same reference numerals, and the components having the same reference numerals have been described in the first embodiment. Therefore, description is abbreviate | omitted in this Embodiment.

<3.1. Configuration of drive unit and rotary damper>
FIG. 2 is a skeleton diagram of the power transmission system in the drive unit 260. 3 and 4 are a front perspective view and a plan view showing an example of the configuration of the rotary damper 270, respectively. Each of FIG. 20 and FIG. 21 is a front view illustrating an example of the configuration of the vibration suppressing unit 275 (275a).

  Similarly to the driving unit 60 of the first embodiment, the driving unit 260 includes the photosensitive drum 13 of each image forming unit 11 and the developing unit 16 (more specifically, the developing roller 17 of each developing unit 16, etc. ) Is given a rotational force. As shown in FIG. 2, the drive unit 260 is obtained by replacing the rotary damper 70 (70Y, 70M, 70C, 70K) with a corresponding rotary damper 170 (170Y, 170M, 170C, 170K).

  For convenience of illustration, FIG. 2 shows the rotary dampers 270Y and 270M among the plurality of rotary dampers 270 (270Y, 270M, 270C, and 270K). In the following description, the rotary dampers 270Y to 270K are also collectively referred to as a rotary damper 270.

  The rotational damper 270 transmits the rotational force applied from the motor 61 to the photosensitive drum 13, similarly to the rotational damper 70 of the first embodiment. As shown in FIGS. 3 to 6, the rotary damper 270 mainly includes an installation part 71, a peristaltic part 72, and a plurality of vibration suppressing parts 275 (275 a to 275 c). .

  A plurality (three in this embodiment) of vibration suppression units 275 (275a to 275c) are attached on the installation unit 71. As shown in FIG. 5, each vibration suppression unit 275 (275a to 275c) has a similar distance from the peristaltic shaft 71a, and the center angle is equiangular (120 degrees in the present embodiment). Has been placed.

  Then, as shown in FIGS. 7 and 8, the vibration suppressing portions 275 (275a to 275c) are deformed along the direction of the arrow AR1, thereby changing the rotational speed of the photosensitive drum 13 (that is, the photosensitive member with respect to a desired speed). The fluctuation of the rotation speed of the drum 13) is suppressed. As shown in FIGS. 5, 6, 20, and 21, the vibration suppressing portion 275 a mainly includes a pair of contact portions 76 (76 a and 76 b), a deforming portion 277, a plurality of pins 78 and 79, have.

  The pair of contact portions 76 (76a, 76b) are disposed on both sides of the deformable portion 277, as shown in FIGS. 7, 8, 20, and 21. The deformation portion 277 is formed by one viscoelastic body (first viscoelastic body), and the pair of contact portions 76 (76a, 76b) applies pressure to the viscoelastic body forming the deformation portion 277. To do. As shown in FIGS. 20 and 21, the shape of the deforming portion 277 in the front view is a trapezoid. One end of the deformable portion 277 in the direction of the arrow AR1 is fixed to the contact portion 76b. On the other hand, the other end of the deformable portion 277 can be deformed along the contact surface with the contact portion 76a.

  Thereby, when the pressing force based on the rotational force is applied from the pair of contact portions 76 (76a, 76b) to the deformable portion 277, the width W of the deformable portion 277 along the contact portion 76a is changed from “W31” to “ It changes to “W32” and the cross-sectional area of the deformed portion 277 increases. Therefore, the elastic coefficient of the deformable portion 277 changes according to the change in the cross-sectional area.

  Further, even when the elastic coefficient of the viscoelastic body forming the deformed portion 277 changes over time when used for a long time under the condition of a constant rotational force (use driving torque) within a predetermined range, By appropriately selecting the material of the elastic body and the shape of the deforming portion 277, the elastic coefficient of the entire vibration suppressing portion 275 is within a certain range. That is, even if the elastic coefficient of the viscoelastic body changes with time, the elastic coefficient of the deformable portion 277 can be maintained equal. Therefore, fluctuations in the rotational speed of the photosensitive drum 13 can be suppressed stably over a long period of time, and the fluctuation range of the rotational speed of the photosensitive drum 13 can be suppressed.

<4. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

  (1) In the first to third embodiments, it has been described that the peristaltic part 72 peristates with respect to the installation part 71. However, the present invention is not limited to this. For example, the installation part 71 may be oscillated with respect to the peristaltic part 72, or both the installation part 71 and the peristaltic part 72 may peristate about the peristaltic shaft 71a. That is, the peristaltic part 72 perturbs relative to the installation part 71.

  (2) In the first to third embodiments, a plurality of vibration suppression units 75 (corresponding to the first embodiment) provided in the installation unit 71 and a plurality of vibration suppression units 175 (second Although it has been described that each of the plurality of vibration suppression units 275 (corresponding to the third embodiment) is deformed, this is not limited to this.

  For example, as long as the elastic coefficient of the entire rotary damper 70 (170, 270) can be maintained constant, only one vibration suppression unit among the plurality of vibration suppression units 75 (175, 275) may be deformed. . In this case, it is sufficient that at least one of the plurality of vibration suppressing portions 75 (175, 275) is deformed.

  (3) In the first to third embodiments, the vibration suppression units 75 and 275 have been described as having the same configuration. However, the present invention is not limited to this. For example, as long as the elastic coefficient of the entire rotary damper 70 (270) can be maintained constant, one vibration suppression unit among the plurality of vibration suppression units 75 (275) may have the above-described configuration.

  (4) In the first to third embodiments, the elastic coefficient of the viscoelastic body has been described as decreasing according to the time of use as shown in FIGS. 12 and 19. It is not limited to. For example, as the viscoelastic body, a material whose elastic coefficient increases according to the elapsed time used may be used.

  For example, the change with time of the deformation portions 77a and 77b in the first embodiment will be described as an example. When the elastic modulus increases according to the elapsed time used, the deformation portions 77a and 77b may be compressed and deformed depending on the elapsed time. It changes from the state which carries out to the state which only the deformation | transformation part 77a compresses.

  Further, in this case, the elastic coefficient (second coefficient) of the deforming part 77b when the deforming parts 77a and 77b are changed from being compressed and deformed to only compressing and deforming is the elastic coefficient of the deforming part 77a (second coefficient). The first coefficient) may be set substantially equal to the amount of change in the elastic coefficient that has changed over time.

  (5) In the first to third embodiments, the elastic coefficient of the vibration suppressing portion 75 (175, 275) distorted by the rotational force has been described as changing with time. However, the present invention is not limited to this. Not a thing. For example, as the vibration suppression unit 75 (175, 275), one that changes according to temperature may be employed. Here, a case where the elastic coefficients of the first to third viscoelastic bodies of the vibration suppressing unit 75 change according to temperature will be described.

  FIG. 22 is a graph illustrating an example of a temperature change of the elastic modulus E. The vertical axis in FIG. 22 represents the elastic coefficient E (Pa) of the viscoelastic body, and the horizontal axis represents the temperature TP (° C.). In addition, the elastic coefficients of the first to third viscoelastic bodies change according to the temperature as indicated by a curve C31 (one-dot chain line), a curve C32 (two-dot chain line), and a curve C33 (dashed line), respectively. In FIG. 22, for example, the temperature TPO is the lower limit temperature of the usable temperature range.

  That is, as shown in FIG. 22, the common points of the curves C31, C32, and C33 decrease as the temperature TP increases, and the inclination with respect to the horizontal axis (TP axis) is the same. The difference between the curves C31, C32, and C33 is that the intercept from the vertical axis (E axis) is different.

  For example, as shown in FIG. 22, in the curve C32, the value of the elastic modulus E is “E30” when the value of the temperature TP is “TP1”. In the curve C33, the value of the elastic modulus E is “E30” when the temperature TP is “TP2”.

  When a certain rotational force is applied to the vibration suppression unit 75 having the first to third viscoelastic bodies, the elastic coefficient of the entire vibration suppression unit 75 is represented by a curve CC3 (solid line) in FIG. To change.

  First, when the temperature TP is in the range of “TP0” to “TP1”, a constant rotational force within a predetermined range is applied to the vibration suppressing unit 75, and the use driving torque is transmitted from the rotary damper 70 to the photosensitive drum 13. In addition, the length D of the deformed portion 77a in the compression direction becomes “D12” or more and less than “D11” due to the temperature change. Thereby, a pair of contact part 76 (76a, 76b) contacts only the deformation | transformation part 77a (refer FIG. 9). Therefore, in the range of the temperature TP from “TP0” to “TP1”, the curve CC3 has the same shape as the curve C31, and the value of the elastic coefficient E of the entire vibration suppression unit 75 is the elastic coefficient of the deformed portion 77a. As shown in FIG. 22, the value is between “E31” and “E32”.

  Next, when a constant rotational force is applied to the vibration suppressing portion 75 in the range of the temperature TP from “TP1” to “TP2”, the length D of the deformable portion 77a in the compression direction is “D13” due to the temperature change. This is less than “D12”. Thereby, a pair of contact part 76 (76a, 76b) contacts deformation | transformation part 77a, 77b (refer FIG. 10). Therefore, in the range of the temperature TP from “TP1” to “TP2”, the curve CC3 has a shape obtained by superimposing the curve C32 on the curve C31, and the value of the elastic coefficient E of the entire vibration suppression unit 75 is the deformed portion 77a and the deformed portion. This is a value obtained by adding the elastic coefficient of 77b, and is a value between “E31” and “E32” as shown in FIG. For this reason, when the deformation | transformation part 77b starts the contact in temperature TP1, the increase amount of the elastic coefficient (curve CC3) of the vibration suppression part 75 whole becomes E30. The value of the increase amount, that is, the elastic coefficient of the deforming portion 77b is set to be equal to the temperature change amount (E32-E31) up to the temperature TP1 of the entire vibration suppressing portion 75.

  Subsequently, when a certain rotational force is applied to the vibration suppressing portion 75 in the range after the temperature TP is “TP2”, the length D of the deformable portions 77a and 77b in the compression direction is equal to or less than “D13” due to a temperature change. It becomes. Thereby, a pair of contact part 76 (76a, 76b) contacts deformation | transformation part 77a, 77b, 77c (refer FIG. 11). Therefore, in the range after the temperature TP is “TP2”, the curve CC3 has a shape in which the two curves C32 and C33 are superimposed on the curve C31. The amount of increase in the elastic coefficient (curve CC3) of the entire vibration suppressing unit 75 at the time of the temperature TP2 is also the value “E30” of the elastic coefficient of the deforming unit 77c. At the time of the temperature TP2, the value of the elastic coefficient of the vibration suppressing unit 75 as a whole is close to the initial value (E32) of the elastic coefficient E (that is, at the temperature TP = “TP0”). Even if the temperature rises, the value between “E31” and “E32” can be maintained.

  Thus, the elastic modulus E of each deformation | transformation part 77 (77a-77c) changes according to temperature. Moreover, the length D of each deformation | transformation part 77 (77a-77c) differs, respectively. Thereby, as shown in FIGS. 9 to 11 and FIG. 22, the number and state of the deforming portions 77 (77a to 77c) acting according to the temperature TP change. Therefore, even if the elastic coefficient E of each deformation | transformation part 77 (77a-77c) changes according to temperature, the elastic coefficient E of the vibration suppression part 75 whole becomes a desired range (E31-E32).

  (6) In the modified example (5) described above, the elastic coefficient of the viscoelastic body has been described as decreasing with increasing temperature, but is not limited thereto. For example, as the viscoelastic body, a material whose elastic coefficient increases as the temperature rises may be used.

  For example, when the temperature change of the deformation | transformation parts 77a and 77b in 1st Embodiment is demonstrated as an example, when an elastic coefficient increases according to temperature rise, depending on temperature, from the state which deformation | transformation parts 77a and 77b compressively deform. Only the deformed portion 77a changes to a state of being compressed and deformed.

  Further, in this case, the elastic coefficient (second coefficient) of the deforming part 77b when the deforming parts 77a and 77b are changed from being compressed and deformed to only compressing and deforming is the elastic coefficient of the deforming part 77a (second coefficient). It may be set substantially equal to the amount of change in the elastic coefficient of the first coefficient) up to that time.

  (7) In the first and third embodiments, the rotational dampers 70 and 270 have been described as having the three vibration suppressing portions 75 and 275, respectively, but the present invention is not limited to this. For example, the number of the vibration suppression units 75 and 275 may be two, or four or more. In other words, the rotary dampers 70 and 270 have at least two or more vibration suppressing portions 75 and 275. Similarly, the rotary damper 170 according to the second embodiment includes at least two vibration suppression units 175.

  (8) In the third embodiment, the deformable portion 277 has been described as being locked by one viscoelastic body, but is not limited thereto. For example, the deformation part 277 may be formed of two or more viscoelastic bodies.

  FIG. 23 to FIG. 25 are front views showing modified examples (375, 475, 575) of the vibration suppressing unit 275 in the third embodiment. For example, as illustrated in FIG. 23, the shape of the deformable portion 377 in the front view is a trapezoidal shape, similar to the deformable portion 277. Further, the outline 378 of the deformable portion 377 in the front view is a curved shape. Thereby, when the pressing force based on the rotational force is applied from the pair of contact portions 76 (76a, 76b) to the deformation portion 377, the cross-sectional area of the deformation portion 377 increases. And the elastic modulus of the deformation | transformation part 377 changes according to the change of a cross-sectional area.

  Further, as illustrated in FIG. 24, the vibration suppressing unit 475 includes a deformed portion 477a fixed to the contact portion 76a and a deformed portion 477b fixed to the contact portion 76b. Further, as shown in FIG. 24, the deforming portions 477a and 477b are in contact with opposing surfaces 478a and 478b having a semicircular shape when viewed from the front. Thereby, when the pressing force based on the rotational force is applied from the pair of contact portions 76 (76a, 76b) to the deformable portions 477a, 477b, the area of the contact surface on the facing surfaces 478a, 478b increases. And the elastic coefficient of the deformation | transformation part 477 changes according to the change of the area of a contact surface.

  As shown in FIG. 25, the deformable portion 577 has one end portion that is linear in a front view and the other end portion that is semicircular. Further, as shown in FIG. 25, the contact portion 576a has a pressing surface having a semicircular shape when viewed from the front. When the pressing force based on the rotational force is applied to the deformed portion 577 from the pair of contact portions 576a and 76b, the area of the contact surface that contacts the contact portion 576a and the deformed portion 577 increases. And the elastic coefficient of the deformation | transformation part 577 changes according to the change of the area of a contact surface.

DESCRIPTION OF SYMBOLS 1,100,200 Image forming apparatus 10 Printer part 20 Exposure scanning part 30 Paper feed part 40 Fixing part 50 Paper discharge part 60, 160, 260 Drive part 61 Motor 70, 170, 270 Rotary damper 75, 175, 275, 375, 475, 575 Vibration suppression part 76 (76a, 76b) Contact part 77 (77a-77c), 177, 277, Deformation part 80 Display part 90 Control part

Claims (12)

A rotary damper for transmitting a rotational force applied from a drive source to a first rotary body,
(a) a plurality of vibration suppression units that each suppress deformation of a rotational speed variation of the first rotating body;
(b) an installation unit provided with the plurality of vibration suppression units;
(c) a peristaltic part that deforms at least one of the plurality of vibration suppressing parts by peristating relative to the installation part around a peristaltic axis;
The attention suppressing unit, which is at least one of the plurality of peristaltic units,
A first deforming portion formed by a first viscoelastic body and a second deforming portion formed by a second viscoelastic body and having an elastic coefficient smaller than that of the first deforming portion;
When the rotary damper transmits a use driving torque within a predetermined range to the first rotating body,
With the change in the elastic modulus of the first deformation part over time,
From the state in which only the first deforming portion is compressed and deformed, the first deforming portion and the second deforming portion are changed in a compressive deforming state, or the first deforming portion and the second deforming portion are in a compressive deformation state. Only the first deformable portion changes to a state in which it is compressed and deformed. The rotary damper according to claim 1, wherein
The first viscoelastic body is made of a material whose elastic modulus decreases with time, and only the first deformable portion is compressively deformed by decreasing the elastic coefficient of the first deformable portion with time. To the state where the first deformable portion and the second deformable portion are compressively deformed,
Alternatively, the first viscoelastic body is made of a material whose elastic coefficient increases with time, and the elastic coefficient of the first deforming part increases with time, whereby the first deforming part and the second deforming part are increased. A rotary damper characterized in that the state changes from a state where the deforming portion compressively deforms to a state where only the first deforming portion compresses and deforms. The rotary damper according to claim 1 or 2,
The elastic modulus of the second deformation part is
When the state is changed from the state in which only the first deforming portion is compressed and deformed to the state in which the first deforming portion and the second deforming portion are compressively deformed or from the state in which the first deforming portion and the second deforming portion are compressed and deformed A rotary damper characterized in that when only the first deforming portion changes into a state of compressive deformation, the first deforming portion is set to be substantially equal to the amount of change in the elastic coefficient that has changed over time. A rotary damper for transmitting a rotational force applied from a drive source to a first rotary body,
(a) a plurality of vibration suppression units that each suppress deformation of a rotational speed variation of the first rotating body;
(b) an installation unit provided with the plurality of vibration suppression units;
(c) a peristaltic part that deforms at least one of the plurality of vibration suppressing parts by peristating relative to the installation part around a peristaltic axis;
The attention suppressing unit, which is at least one of the plurality of peristaltic units,
A first deforming portion formed by a first viscoelastic body and a second deforming portion formed by a second viscoelastic body and having an elastic coefficient smaller than that of the first deforming portion;
When the rotary damper transmits a use driving torque within a predetermined range to the first rotating body,
Along with a change in the elastic modulus of the first deformation part due to a temperature change,
From the state in which only the first deforming portion is compressed and deformed, the first deforming portion and the second deforming portion are changed in a compressive deforming state, or the first deforming portion and the second deforming portion are in a compressive deformation state. Only the first deformable portion changes to a state in which it is compressed and deformed. The rotary damper according to claim 4, wherein
The first viscoelastic body is made of a material whose elastic modulus decreases as the temperature rises,
At the temperature TP0, which is the lower limit of use of the rotary damper, only the first deformable portion is compressively deformed,
As the elastic modulus of the first deformable portion decreases as the temperature rises, the first deformable portion and the second deformable portion change into a state of compressive deformation at temperature TP1,
The elastic coefficient of the second deformable portion at the temperature TP1 is set to be approximately equal to the change amount of the elastic coefficient that the first deformable portion has changed from the temperature TP0 to the temperature TP1. Rotating damper. The rotary damper according to claim 4, wherein
The first viscoelastic body is made of a material whose elastic modulus increases as the temperature rises,
At the temperature TP0 that is the lower limit of use of the rotary damper, the first deformation portion and the second deformation portion are compressively deformed,
As the elastic modulus of the first deformable portion increases as the temperature rises, only the first deformable portion changes into a state of compressive deformation at temperature TP1,
The elastic coefficient of the second deformable portion at the temperature TP1 is set to be approximately equal to the change amount of the elastic coefficient that the first deformable portion has changed from the temperature TP0 to the temperature TP1. Rotating damper. The rotary damper according to any one of claims 1 to 6,
The rotary damper characterized in that a length of the first deformable portion in the compression direction is larger than a length of the second deformable portion. The rotary damper according to any one of claims 1 to 7,
A pair of contact parts that compressively deform the first viscoelastic body are disposed on both sides of the first deformation part,
A pair of contact portions for compressively deforming the second viscoelastic body is disposed on both sides of the second deformation portion,
The pair of contact portions of the first deformable portion and the pair of contact portions of the second deformable portion are configured to have different angles, the same radius, and the same phase with respect to the peristaltic shaft. Rotating damper characterized by that. A rotary damper for transmitting a rotational force applied from a drive source to a first rotary body,
(a) a plurality of vibration suppression units that each suppress deformation of a rotational speed variation of the first rotating body;
(b) an installation part provided with the plurality of vibration absorbing parts;
(c) a peristaltic part that deforms at least one of the plurality of vibration suppression parts by peristating relative to the installation part around a peristaltic axis;
With
The attention suppressing unit, which is at least one of the plurality of vibration suppressing units,
(a-1) a deformed portion formed of one or more viscoelastic bodies,
(a-2) a pair of contact portions that are arranged on both sides of the deformation portion in the compression direction, and apply pressure to the viscoelastic body;
Have
A pressing force based on the rotational force is applied to the deformation portion from the pair of contact portions,
Even when the elastic coefficient of the deforming portion changes when the rotating damper transmits the use driving torque within a predetermined range to the first rotating body, the rotating damper is in contact with the pair of contact portions of the deforming portion. The rotary damper characterized in that the elastic modulus of the vibration suppressing portion is maintained equal by changing the contact cross-sectional area. The rotary damper according to claim 9, wherein
The rotary damper according to claim 1, wherein an elastic coefficient of the deformed portion that is distorted by the rotational force changes with time. The rotary damper according to claim 9 or 10,
The rotary damper according to claim 1, wherein an elastic coefficient of the deformable portion distorted by the rotational force changes according to a temperature change. An image forming apparatus for forming an image on a recording material,
A rotary damper which is described in any one of claims 1 to 11 and which transmits a rotational force applied from the drive source,
A photosensitive member rotating unit that is provided as the first rotating member and rotates by a rotating force transmitted from the rotating damper;
An image forming apparatus comprising:

Images