JP2006300230A - Rotating body driving apparatus and image recording apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating body that causes problems such as banding and color misregistration without increasing the size of the apparatus due to an increase in arrangement space by a large-diameter flywheel, and without increasing the manufacturing cost due to a complicated output motor and configuration Suppresses fluctuations in rotation speed.
A motor 38 as a drive source for driving a photosensitive drum 17d in an image recording apparatus and a flywheel 41 for suppressing fluctuations in the rotational speed of the photosensitive drum driven by the motor are provided. On the power transmission path for transmitting the driving force to the photosensitive drum, there is provided a connecting shaft 43 having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity, and a flywheel is provided on the connecting shaft. Is attached.
[Selection] Figure 4

Description

  The present invention relates to a driving device for driving a rotating body such as a photosensitive drum and a roller in an image recording apparatus and an image recording apparatus including the driving apparatus, and more particularly, to a rotating body having a flywheel that suppresses fluctuations in the rotational speed of the rotating body. The present invention relates to a driving device and an image recording apparatus including the driving device.

  In the image forming apparatus, when the rotational speed of the photosensitive drum varies, the scanning pitch in the sub-scanning direction changes, and density unevenness in the sub-scanning direction, so-called banding, occurs on the image. For the purpose of reduction, a configuration in which a flywheel is provided coaxially on the photosensitive drum may be employed. In this configuration, by increasing the diameter of the flywheel, the torsional natural frequency of the drive system can be set much lower than the meshing frequency of the gears and pulleys, and the rotational speed fluctuation suppressing effect can be improved. .

  In a color image forming apparatus, a so-called tandem type configuration in which a plurality of photosensitive drums for each color component of yellow, magenta, cyan, and black are arranged along an intermediate transfer belt is widely used. In this configuration, if the rotational speeds of the photosensitive drums for each color are different, the position of the toner image for each color formed on the photosensitive drum may be shifted, so-called color shift may occur. The flywheel is also effective in reducing this.

However, in the tandem type color image forming apparatus, the large diameter of the flywheel is avoided by avoiding the disadvantage that the outer diameter of the flywheel is limited in order to avoid mutual interference of flywheels coaxially provided on the photosensitive drum. In order to achieve this, there is known a configuration in which flywheels are alternately arranged by shifting the mounting position of the flywheel in the axial direction (see Patent Document 1). In addition, in order to suppress fluctuations in the rotational speed of the photosensitive drum without increasing the diameter of the flywheel, a configuration having a dynamic vibration absorber made up of a rotary inertia body and an elastic body is known (patent) Reference 2).
JP-A-8-194354 JP 2000-85206 A

  However, with the conventional technology that shifts the mounting position of the large-diameter flywheel in the axial direction as described above, a large output drive motor is used to ensure a predetermined start-up time and an extra space in the axial direction is secured. Therefore, there arises a disadvantage that the manufacturing cost increases and the apparatus becomes large. Moreover, in the conventional technique which provides a dynamic vibration absorber as mentioned above, there exists a difficulty that a structure becomes complicated and manufacturing cost increases.

  The present invention has been devised to solve such problems of the prior art, and its main purpose is to increase the size of the apparatus by increasing the arrangement space by a large-diameter flywheel and to drive a large output. Rotating body drive device configured to be able to suppress fluctuations in the rotational speed of the rotator causing inconveniences such as banding and color misregistration without incurring an increase in manufacturing cost due to a complicated motor and configuration, and the same Is to provide an image recording apparatus including the above.

  In order to solve such a problem, in the driving device for a rotating body according to the present invention, a motor as a driving source for driving the rotating body, and the rotating body driven by the motor, as shown in claim 1. An elastic cylinder having a flywheel that suppresses fluctuations in rotational speed, and is formed hollow by a synthetic resin material having a required spring rigidity on a power transmission path that transmits the driving force of the motor to the rotating body A connecting shaft provided with a portion was provided, and the flywheel was attached to the connecting shaft.

  According to this, even in the case of a small-diameter flywheel, the torsional natural frequency of the elastic cylindrical part made of synthetic resin is used to determine the vibration frequency of the motor and rotation transmission elements such as gears and pulleys that cause banding and color shift. Compared to metal shafts that are generally used, the elastic cylindrical part made of synthetic resin has a better ability to damp vibrations such as motors. Therefore, the fluctuation component of the rotational speed on the input side caused by the vibration of the motor or the like is not easily transmitted to the output side. For this reason, a small-diameter flywheel and a small output motor are adopted, and fluctuations in the rotational speed of the rotating body can be significantly suppressed without increasing the manufacturing cost and complicating the configuration.

  According to a second aspect of the present invention, the rotating body drive device further includes a rotational transmission element disposed coaxially with the coupling shaft to transmit the driving force of the motor to the coupling shaft. The transmission element and the connecting shaft may be formed separately from each other and fastened to each other by a screw screwed in the axial direction.

  The rotating body drive device further includes a rotation transmission element coaxially disposed on the connecting shaft so as to transmit the driving force of the motor to the connecting shaft. The rotation transmission element and the connecting shaft may be formed integrally with a synthetic resin material.

  When the rotation transmission element is coaxially arranged on the connecting shaft in this way, the support shaft of the rotation transmission element and the support shaft of the rotary body are arranged substantially coaxially, but are configured separately from each other. Even when the degree of coaxiality between the two is low, if the rotation transmission element is held at a constant attitude, only the connecting shaft is bent, and the amount and direction of the bending are held constant during rotation. Speed fluctuation can be suppressed. For this reason, it is not necessary to ensure the high degree of coaxiality between the support shaft of the rotary transmission element and the support shaft of the rotary body, and therefore, the mounting accuracy of the support shaft of the rotary body is ensured to be high while the support of the rotary transmission element is supported. It is possible to reduce the number of manufacturing steps by setting the shaft mounting accuracy to be relatively low.

  As described above, when the rotational transmission element and the coupling shaft that are separate from each other are fastened with screws, or the rotational transmission element and the coupling shaft are integrally formed of a synthetic resin material, the support shaft of the rotational transmission element is obtained. Even if the concentricity between the rotating shaft and the support shaft of the rotating body is low, one end of the connecting shaft is firmly fixed to the rotary transmission element, so that the bending deformation of the connecting shaft can be held more constant, The fluctuation can be further suppressed.

  The rotational transmission element is a gear or a pulley, and transmits the driving force of the motor in cooperation with the rotational transmission element on the driving side provided on the output shaft of the motor.

  In the rotating body drive device, as shown in claim 4, the connecting shaft includes a joint in which a joint member provided on the shaft on the rotating body side is detachably fitted in the axial direction. Can do. According to this, the detachment of the rotating body becomes easy and the efficiency of maintenance work can be increased.

  Further, in the rotating body drive device according to the present invention, as shown in claim 5, a motor as a drive source for driving the rotating body and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor And a connecting shaft having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity is provided on a power transmission path for transmitting the driving force of the motor to the rotating body. The connecting shaft is disposed on the input side of the rotating shaft to which the flywheel is attached.

  According to this, even in the case of a small-diameter flywheel, the torsional natural vibration frequency of the elastic cylindrical portion made of synthetic resin is changed to the vibration frequency of the motor or the torsional natural frequency of the rotating shaft, which causes banding and color shift. Compared to metal shafts that are generally used, the elastic cylindrical part made of synthetic resin is superior to metal shafts in general use. The fluctuation component of the rotational speed on the input side caused by vibration is hardly transmitted to the output side. For this reason, a small-diameter flywheel and a small output motor are adopted, and fluctuations in the rotational speed of the rotating body can be significantly suppressed without increasing the manufacturing cost and complicating the configuration.

  In this case, a configuration in which a rotation transmission element (gear or pulley) for transmitting the driving force of the motor to the connection shaft is directly provided on the connection shaft is possible. At this time, the connection shaft is connected to the rotation transmission element with respect to the rotation shaft. If the configuration is such that relative rotation is impossible at a position spaced apart from the mounting position in the axial direction, the elastic cylindrical portion can function effectively.

  According to another aspect of the present invention, there is provided a driving device for a rotating body, a motor as a driving source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor. And the flywheel is held by a holding member having an elastic cylindrical portion formed hollow with a synthetic resin material having a required spring rigidity, and the holding member provides the driving force of the motor. The rotary shaft on the power transmission path for transmitting to the rotating body is externally mounted, and is coupled to the rotary shaft so as not to be relatively rotatable at a position spaced from the flywheel mounting position in the axial direction.

  According to this, even in the case of a small-diameter flywheel, the torsional natural vibration frequency of the elastic cylindrical portion made of synthetic resin is changed to the vibration frequency of the motor or the torsional natural frequency of the rotating shaft, which causes banding and color shift. Compared to metal shafts that are generally used, the elastic cylindrical portion made of synthetic resin is superior to metal shafts that are generally used. Because the force that suppresses the vibration on the input side caused by the excitation force of the motor or the like acts on the rotating shaft in cooperation with the ring-shaped part and the flywheel, the rotating shaft generates vibration that becomes a fluctuation component of the rotational speed It becomes difficult to do. For this reason, a small-diameter flywheel and a small output motor are adopted, and fluctuations in the rotational speed of the rotating body can be significantly suppressed without increasing the manufacturing cost and complicating the configuration.

  Further, in the rotating body drive device according to the present invention, as shown in claim 7, a motor as a driving source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor The flywheel is held by a holding member having an elastic cylindrical portion formed hollow with a synthetic resin material having a required spring rigidity, and this holding member is externally attached to the output shaft of the motor. In addition, the output shaft is coupled so as not to be relatively rotatable at a position spaced in the axial direction from the flywheel mounting position.

  According to this, even in the case of a small-diameter flywheel, the torsional natural vibration frequency of the elastic cylindrical portion made of synthetic resin is the same as the vibration frequency of the motor and the torsional natural vibration of the motor output shaft that cause banding and color shift. Compared to the number of metal shafts, the elastic cylindrical portion made of synthetic resin is superior to metal shafts that are generally used in the ability to attenuate vibrations caused by motors. Since the elastic cylindrical portion and the flywheel cooperate with each other, and the force that suppresses the vibration generated by the excitation force of the motor acts on the output shaft of the motor, the vibration that becomes the fluctuation component of the rotational speed is applied to the output shaft of the motor. It becomes difficult to occur. For this reason, a small-diameter flywheel and a small output motor are adopted, and fluctuations in the rotational speed of the rotating body can be significantly suppressed without increasing the manufacturing cost and complicating the configuration.

  In the driving device for the rotating body, as shown in claim 8, the synthetic resin material forming the elastic cylindrical portion may be polyacetal. According to this, the elastic cylindrical portion can be made to have an appropriate spring rigidity, and moreover, it can be made to have high mechanical strength, particularly high durability against repeated loads.

  The rotating body driving device can be applied to an image recording apparatus. That is, the rotating body is a photosensitive drum for each color, and a plurality of them can be arranged in parallel to each other. According to this, since fluctuations in the rotation speed of the photosensitive drum are suppressed, banding caused by a change in the scanning pitch in the sub-scanning direction, and sub-transfer of the toner image for each color formed on the photosensitive drum for each color. Color misregistration caused by positional deviation in the scanning direction can be reduced.

  In addition, since the support shaft of the rotary transmission element and the support shaft of the rotary body are configured separately, the mounting accuracy of the support shaft of the photosensitive drum as the rotary body is independent of the support shaft of the rotary transmission element. By setting a high value, it is possible to ensure a high degree of parallelism between the photosensitive drums for each color, and thereby the positional deviation in the main scanning direction of the toner image for each color formed on the photosensitive drum for each color. It is possible to reduce the color misregistration caused by.

  The rotating body may be a support roller around which the intermediate transfer belt is wound. According to this, since the fluctuation of the rotation speed of the support roller is suppressed, the traveling speed of the intermediate transfer belt can be kept constant with high accuracy, and thereby the speed difference between the photosensitive drum and the intermediate transfer belt. Accordingly, it is possible to avoid the disadvantage that the toner image transferred from the photosensitive drum to the intermediate transfer belt is displaced or a load is applied to the intermediate transfer belt.

  As described above, according to the present invention, even in the case of a small-diameter flywheel, the torsional natural vibration frequency of the elastic cylindrical portion made of synthetic resin depends on the vibration frequency of the motor, the meshing of the rotation transmission element such as a gear and a pulley, and the like. It can be set lower than the vibration frequency, and the elastic cylindrical part made of synthetic resin has an excellent high vibration damping capability. Fluctuation component becomes difficult to be transmitted to the output side. For this reason, adopting a small-diameter flywheel and a small output motor, without increasing the size of the device due to the increase in the arrangement space by the large-diameter flywheel, and without increasing the manufacturing cost due to the complication of the large output drive motor and configuration, A great effect can be obtained in forming a high-quality image by suppressing fluctuations in the rotational speed of the rotating body, which causes problems such as banding and color shift.

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

  FIG. 1 is a schematic cross-sectional view showing an image forming apparatus to which the present invention is applied. The image forming apparatus includes an image forming unit 1 that forms an image on recording paper through each process of exposure, development, transfer, and fixing. The image forming unit 1 includes a paper cassette 3 in a paper feeding unit 2. The stored recording paper is sequentially fed through the paper feed path A, and the recording paper on which a required image is formed by the image forming unit 1 is discharged onto the tray of the paper discharge unit 4 through the paper discharge path B. Further, by feeding the recording sheet sent out from the image forming unit 1 again to the image forming unit 1 via the reverse path C, it is possible to form images on both sides of the recording sheet.

  Further, the image forming apparatus includes a document reading unit 5 that reads an image of a document. The image forming unit 1 forms an image based on the image data acquired by the document reading unit 5 and converts the document image. It can be copied on recording paper.

  The image forming unit 1 forms a color image on recording paper, and includes a plurality of process units (image forming units) 11a to 11d that form toner images for respective color components of yellow, magenta, cyan, and black. ing. These process units 11a to 11d have the same configuration.

  In each of the process units 11a to 11d, a light beam for exposure is scanned from an LSU (laser scanning unit) (not shown) on the image forming surfaces of the photosensitive drums 17a to 17d uniformly charged by the charging unit 16. As a result, electrostatic latent images are formed, and the electrostatic latent images on the photosensitive drums 17a to 17d are developed with toner supplied from the developing device 18, and single-color toner images for the respective color components are formed on the photosensitive drums 17a to 17d. Formed on the image forming surface.

  These process units 11a to 11d are arranged along the intermediate transfer belt 21, and the primary transfer roller 22 for each color that presses the intermediate transfer belt 21 from the back surface, thereby the photoreceptors of the process units 11a to 11d. The toner images for the respective colors formed on the drums 17a to 17d are sequentially transferred onto the intermediate transfer belt 21 and superimposed. The toner remaining on the image forming surfaces of the photosensitive drums 17a to 17d after the transfer is removed by the cleaning unit 19.

  The intermediate transfer belt 21 is wound around a pair of support rollers 23 and 24, and a secondary transfer roller 25 is disposed opposite to the one support roller 23, and the secondary transfer roller 25, the intermediate transfer belt 21, In the meantime, the recording paper from the paper feeding unit 2 is fed, so that the toner image superimposed on the intermediate transfer belt 21 is transferred to the recording paper. The recording paper on which the toner image has been transferred is conveyed to the fixing unit 26, where the toner image synthesized by heat and pressure is fixed on the recording paper.

  The intermediate transfer belt 21, the support rollers 23 and 24, and the primary transfer roller 22 are integrated by a frame material (not shown) that supports them, and constitute a transfer unit that can be attached to and detached from the housing of the image forming apparatus. is doing.

  In each of the process units 11a to 11d, a process cartridge 20 formed by integrating the photosensitive drums 17a to 17d, the charging unit 16, and the cleaning unit 19 is formed so as to be separable from the developing unit 18, and the photosensitive drum It is detachable in the axial direction of 17a to 17d.

  FIG. 2 is a perspective view showing a driving device for the photosensitive drum shown in FIG. This is to drive the photosensitive drums 17a to 17d as rotating bodies, and a first drive mechanism 31 that rotates the yellow, magenta, and cyan photosensitive drums 17a to 17c in conjunction with each other, and this Independent of the first drive mechanism 31, it has a second drive mechanism 32 that rotates the black photosensitive drum 17 d, and both the first and second drive mechanisms 31. 32 are operated together, and only the second drive mechanism 32 is operated and the first drive mechanism 31 is stopped at the time of monochrome image formation.

  A first drive mechanism 31 for driving the yellow, magenta, and cyan photoconductor drums 17a to 17c includes a motor 34 as a drive source and a gear provided coaxially with the photoconductor drums 17a to 17c. (Rotation transmission elements) 35a to 35c and idler gears 36 and 37 for rotating these gears 35a to 35c in an interlocking manner. The second drive mechanism 32 for driving the black photosensitive drum 17d has a motor 38 as a drive source and a gear (rotational transmission element) 35d provided coaxially with the photosensitive drum 17d. Yes.

  Between each of the photosensitive drums 17a to 17d and the gears 35a to 35d, a flywheel 41 that suppresses fluctuations in the rotational speed of the photosensitive drums 17a to 17d is provided. In order to transmit the rotational force of the gears 35a to 35d driven by the motor 38 to the support shaft 42 of the photosensitive drums 17a to 17d, the gear 35a to 35d is externally mounted on a connecting shaft 43 provided coaxially with the support shaft 42.

  FIG. 3 is a front view showing a main part of the drive device for the photosensitive drum shown in FIG. In the first drive mechanism 31 that drives the yellow, magenta, and cyan photoconductive drums 17a to 17c, the magenta and cyan gears 35b and 35c positioned in the middle are provided on the gear 45 provided on the output shaft of the motor 34. The magenta and cyan photosensitive drums 17b and 17c are driven, the idler gear 36 is engaged with the gear 45 provided on the output shaft of the motor 34, and the idler gear 37 that is engaged with the idler gear 36 is positioned at the end. The yellow gear 35a meshes with each other, and the yellow photosensitive drum 17a is driven.

  In the second drive mechanism 32 for driving the black photosensitive drum 17d, the gear 35d is engaged with the gear 46 provided on the output shaft of the motor 38, and the black photosensitive drum 17d is driven.

  FIG. 4 is a cross-sectional view showing a main part of the drive device for the photosensitive drum shown in FIG. Here, the second drive mechanism 32 for driving the black photosensitive drum 17d is shown. The connecting shaft (elastic cylindrical portion) 43 on which the flywheel 41 is packaged is formed in a hollow cylindrical shape by a synthetic resin material having a required spring rigidity, and the mounting portion 51 of the flywheel 41 is at an intermediate position in the axial direction. Is provided. The synthetic resin material forming the connecting shaft 43 is preferably polyacetal.

  The connecting shaft 43 includes an input side joint portion 52 to which a gear 35d that rotates in conjunction with the output shaft of the motor 38 is connected in a relatively non-rotatable manner at one end, and an end portion of the support shaft 42 of the photosensitive drum 17d at the other end. The joint member 53 provided in the is provided with an output side joint portion 54 that is detachably fitted in the axial direction.

  The joint member 53 has a substantially cylindrical shape with a center hole 56 into which the end of the support shaft 42 of the photosensitive drum 17d is fitted, and a pin 57 that penetrates the joint member 53 and the support shaft 42 in the diameter direction. Further, the support shaft 42 is fixed so as not to be relatively displaceable in the rotational direction and the axial direction.

  A so-called involute spline is formed on the outer peripheral surface of the fitting portion 58 of the joint member 53 with the connecting shaft 43 in which axial ridges are arranged in the circumferential direction. On the other hand, the inner periphery of the output-side joint portion 54 of the connecting shaft 43 has a cross-sectional shape complementary to the fitting portion 58 of the joint member 53, and the joint member 53 is axial with respect to the output-side joint portion 54. Since the two cannot be relatively rotated in the fitted state, the rotational force of the connecting shaft 43 is transmitted to the support shaft 42 of the photosensitive drum 17d.

  The support shaft 42 of the photosensitive drum 17 d is supported by the frame member 62 via the bearing 61, and its mounting position is defined by the positioning pin 63. As described above, the photosensitive drum 17d is integrated with the charging unit and the cleaning unit to constitute the process cartridge 20, and the process cartridge 20 can be attached to and detached from the photosensitive drum 17d in the axial direction.

  When the process cartridge 20 is mounted, the joint member 53 at the end of the support shaft 42 passes through the mounting hole 64 and is guided by a peripheral member such as the outer wall of the adjacent developing device. At the same time, the positioning pin 63 is inserted into the positioning hole 65, and the photosensitive drum 17d is positioned and fixed with high accuracy.

  The gear 35d is a helical gear, and includes a bearing boss 71 that protrudes toward the photosensitive drum 17d from a gear main body portion 70 having teeth that mesh with a gear 46 provided on the output shaft of the motor 38 on the outer periphery. The bearing boss 71 is rotatably fitted to a support shaft 73 fixed to a frame member 72 that supports the motor 38. The base portion 75 of the support shaft 73 is fitted into an attachment hole 76 formed in the frame member 72 and is firmly fixed to the frame member 72 by caulking.

  The connecting shaft 43 surrounds the bearing boss 71, the input side joint 52 is connected to the base of the bearing boss 71 in the gear 35d, and the outer peripheral surface of the fitting portion 78 with the connecting shaft 43 in the gear 35d A so-called involute spline in which axial ridges are arranged in the circumferential direction is formed. On the other hand, the inner periphery of the input side joint portion 52 of the connecting shaft 43 has a cross-sectional shape complementary to the fitting portion of the gear 35d, and both are connected so as not to be relatively rotatable, and the rotational force of the gear 35d is increased. It is transmitted to the connecting shaft 43.

  Further, the gear 35d and the connecting shaft 43 are fixed by a screw 79. The screw 79 penetrates the gear main body portion 70 of the gear 35d in the axial direction and is formed on the outer periphery of the input side joint portion 52 of the connecting shaft 43. Screwed into the connecting portion 80. A plurality of, for example, three screws 79 are provided at equal intervals in the circumferential direction so as to be firmly fixed to the gear main body 70 of the gear 35d without rattling.

  The flywheel 41 is formed by superposing a plurality of steel plates 82, and is fixed by screws 83 to a mounting portion 51 that extends outward in the radial direction on the connecting shaft 43. A plurality of, for example, three screws 83 are provided at equal intervals in the circumferential direction so that the flywheel 41 is firmly fixed to the mounting portion 51 without rattling.

  FIG. 5 is a perspective view schematically showing a drive device for the photosensitive drum shown in FIG. As described above, the driving force of the motor 38 is transmitted to the support shaft 42 through the gear 46, the gear 35d, the connecting shaft 43, and the joint member 53 in order, and the photosensitive drum 17d rotates. Synthetic resin coupling shafts with excellent inertial force and vibration damping capability of the flywheel 41 due to gear speed changes caused by the gear meshing in the drive system reaching the coupling shaft 43 via the gears 46 and 35d. 43, and the suppression of fluctuations in rotational speed by the flywheel 41 and the connecting shaft 43 is particularly effective for removing high-frequency components.

  FIG. 6 is a cross-sectional view schematically showing a drive device for the photosensitive drum shown in FIG. The bearing boss 71 of the gear 35d protrudes toward the photosensitive drum 17d so as to be inserted into the cylindrical connecting shaft 43, and a long fitting length between the bearing boss 71 and the support shaft 73 can be ensured. Further, the posture of the gear 35d can be held constant and with high accuracy, whereby fluctuations in the rotational speed of the photosensitive drum 17d caused by the posture change of the gear 35d can be suppressed.

  The support shaft 42 of the photosensitive drum 17d and the support shaft 73 of the gear 35d are arranged substantially coaxially, but are configured separately from each other, and the degree of coaxiality between the two is low. Even when the deviation D is large, the posture of the gear 35d is held constant by the rigidity of the bearing boss 71 and the support shaft 73, and the input side joint portion 52 of the connecting shaft 43 is firmly fixed to the gear 35d by the screw 79. As a result, only the connecting shaft 43 is bent, and the amount and direction of the bending are kept constant even during rotation, so fluctuations in the rotational speed of the photosensitive drum 17d can be suppressed.

  The configuration of each part from the gear 35d to the photosensitive drum 17d in the second driving mechanism 32 that drives the black photosensitive drum 17d illustrated in FIGS. 4, 5, and 6 is cyan, magenta, and yellow. The same applies to the first drive mechanism 31 that drives the photosensitive drums 17a to 17c.

  FIG. 7 is a schematic perspective view showing another example of the rotating body driving device according to the present invention. This drives the support roller 24 on the drive side of the pair of support rollers 23 and 24 around which the intermediate transfer belt 21 is wound, and, like the connecting shaft 43, has a required spring rigidity. A connecting shaft 101 formed in a hollow cylindrical shape by a resin material is provided, and a flywheel 102 is attached to an intermediate position in the axial direction.

  As in the above example, the input side joint portion 103 of the connecting shaft 101 is connected to the gear 106 that meshes with the gear 105 provided on the output shaft of the motor 104 so as not to rotate relative thereto, and the driving force of the motor 104 is input. . On the other hand, the output side joint portion 107 is connected to a shaft 111 provided with a gear 110 that meshes with a gear 109 provided on the support shaft 108 of the support roller 24 so as not to be relatively rotatable. Then, the support roller 24 rotates.

  Here, if a change in rotational speed due to the meshing of the gear 105 and the gear 106 occurs in the drive system from the motor 104 to the connecting shaft 101, the inertial force of the flywheel 102 and the input side joint are similar to the above example. The high-frequency component of the rotational speed fluctuation component is removed by the vibration damping capability of the section 103, and thereby the fluctuation of the rotational speed of the support roller 24 is greatly suppressed. Can be stabilized.

  FIG. 8 is a cross-sectional view showing a modification of the photosensitive drum driving apparatus shown in FIG. Here, the rotation transmission member 121 having a configuration in which the gear 35d and the connecting shaft 43 in the above example are integrated is provided. This rotation transmission member 121 is formed in a hollow cylindrical shape with a gear portion 122 that meshes with a gear on the motor side in the same manner as the gear 35d in the above example, and an attachment portion of the flywheel 41 at an intermediate position in the axial direction thereof And a connecting shaft portion 123 provided with 51, and these portions are integrally formed of a synthetic resin material having a required spring rigidity.

  The connecting shaft 123 is formed in such a manner that it extends toward the photosensitive drum 17d so as to surround a bearing boss 126 that fits into a support shaft 127 whose base is fixed to the frame member 72. In the same manner as the connecting shaft 43, a joint member 53 provided at the end of the support shaft 42 of the photosensitive drum 17d is provided with an output side joint portion 125 that is detachably fitted in the axial direction.

  In this configuration, as with the connecting shaft 43 in the above example, the inertial force of the flywheel 41 and the vibration damping ability of the connecting shaft portion 123 against fluctuations in the rotational speed of the drive system from the motor 38 to the gear portion 122. As a result, the fluctuation component of the rotational speed at the gear part 122 is hardly transmitted to the output side joint part 125, and the fluctuation of the rotational speed of the photosensitive drum 17d can be suppressed.

  FIG. 9 is a schematic cross-sectional view showing another example of the rotating body driving apparatus according to the present invention. Here, as in the above example, a motor 38 as a drive source for driving the photosensitive drum 17d as a rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the photosensitive drum 17d driven by the motor 38. 41. However, unlike the above example, the flywheel 41 is attached to the connecting shaft 132 provided with the elastic cylindrical portion 131 formed hollow by a synthetic resin material having a required spring rigidity. It is provided on the input side of the rotating shaft 133.

  In particular, here, a gear portion (rotational transmission element) 134 that transmits the driving force of the motor 38 to the connecting shaft 132 is provided integrally with the connecting shaft 132, and the driving force of the motor 38 rotates via the connecting shaft 132. Input to the axis 133.

  The connecting shaft 132 is mounted on the rotating shaft 133 and is coupled to the rotating shaft 133 so as not to rotate relative to the rotating shaft 133 at a position spaced apart from the gear portion 134 in the axial direction. Specifically, the connecting shaft 132 is connected to one end of the connecting shaft 132. The other end of the connecting shaft 132 (the end opposite to the gear portion 134) is provided with a fastening pin 135 that prevents relative rotation with respect to the rotating shaft 133, and the side on which the gear portion 134 is provided. The end of the connecting shaft 132 is rotatable relative to the rotating shaft 133 within a range allowed by elastic deformation of the elastic cylindrical portion 131.

  In addition, the flywheel 41 is attached to the rotating shaft 133 so as not to be relatively rotatable by a fastening pin 136. A joint member 142 provided at the end of the support shaft 42 of the photosensitive drum 17d is detachably fitted in the axial direction to a joint member 141 provided at the end of the rotating shaft 133, and In the fitted state, the two cannot rotate relative to each other, and the rotational force of the rotary shaft 133 is transmitted to the support shaft 42 of the photosensitive drum 17d. The joint members 141 and 142 are attached to the rotation shaft 133 and the support shaft 42 so as not to rotate relative to each other by fastening pins 143 and 144, respectively. The rotating shaft 133 is supported by bearings 145 and 146, and the support shaft 42 of the photosensitive drum 17 d is supported by a bearing 147.

  FIG. 10 is a schematic cross-sectional view showing another example of the rotating body driving apparatus according to the present invention. Here, as in the above example, a motor 38 as a drive source for driving the photosensitive drum 17d as a rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the photosensitive drum 17d driven by the motor 38. However, unlike the above example, the flywheel 41 is held by a holding member 152 having an elastic cylindrical portion 151 formed hollow by a synthetic resin material having a required spring rigidity. The holding member 152 is mounted on the rotary shaft 153 and is coupled to the rotary shaft 153 so as not to rotate relative to the rotary shaft 153 at a position spaced apart from the mounting position of the flywheel 41 in the axial direction.

  In particular, here, a fastening pin 154 that prevents relative rotation with respect to the rotating shaft 153 is provided at one end of the holding member 152 (an end opposite to the flywheel 41), and the other end of the holding member 152 (flywheel). 41) is rotatable relative to the rotation shaft 153 within a range allowed by elastic deformation of the elastic cylindrical portion 151. The flywheel 41 is fixed to a mounting portion 155 that extends outward in the radial direction in the holding member 152 with a screw 156.

  Further, a gear 157 that meshes with a gear 46 provided on the output shaft of the motor 38 is attached to the rotating shaft 153 so as not to be relatively rotatable by a fastening pin 158, and the driving force of the motor 38 is transmitted to the rotating shaft 153. The

  FIG. 11 is a schematic cross-sectional view showing another example of the rotating body driving apparatus according to the present invention. Here, as in the above example, a motor 38 as a drive source for driving the photosensitive drum 17d as a rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the photosensitive drum 17d driven by the motor 38. 41, and the flywheel 41 is held by a holding member 172 having an elastic cylindrical portion 171 formed hollow by a synthetic resin material having a required spring rigidity. Unlike the flywheel 41, the holding member 172 of the flywheel 41 is externally mounted on the output shaft 173 of the motor 38, and is relatively non-rotatable with respect to the output shaft 173 at a position spaced axially from the mounting position of the flywheel 41. Are combined.

  In particular, here, the portion of the output shaft 173 that extends to the opposite side across the motor body 176 and the gear 46 that meshes with the gear 175 provided on the rotation shaft 174 to transmit the driving force of the motor 38 to the rotation shaft 174. A holding member 172 of the flywheel 41 is attached to 173a.

  As in the above example, the holding member 172 is attached to the output shaft 173 by the fastening pin 177 so as not to rotate relative to the output shaft 173. The fastening pin 177 is connected to one end of the holding member 172 (the end opposite to the flywheel 41). The other end of the holding member 172 (the end where the flywheel 41 is provided) can be rotated relative to the output shaft 173 within a range permitted by elastic deformation of the elastic cylindrical portion 171. ing. The flywheel 41 is fixed by screws 179 to a mounting portion 178 that extends radially outward in the holding member 172 in a flange shape.

  FIG. 12 shows the experimental results of the rotating body driving apparatus according to the present invention. Here, Example 1 has the configuration shown in FIG. 4 and includes four discs 82 constituting the flywheel 41, and Example 2 has the configuration shown in FIG. Therefore, the number of discs 82 constituting the flywheel 41 is eight. In the comparative example, the flywheel 41 is not attached.

  (A) shows variations in color misregistration in terms of SN ratio (db), which is 15.06 in the comparative example, 20.56 in the first example, and 17.19 in the second example. (B) shows color shift sensitivity (db), which is 32.28 in the comparative example, 31.11 in the example 1, and 31.66 in the example 2. (C) shows the variation in banding in terms of SN ratio (db), which is 10.53 in the comparative example, 20.54 in the first example, and 31.41 in the second example. (D) shows the banding sensitivity (db), which is 13.39 in the comparative example, 6.58 in the first example, and 4.73 in the second example.

  In (A) color shift variation and (C) banding variation, the larger the value, the smaller the variation and the greater the resistance to disturbance. (B) Color shift sensitivity and (D) Banding variation In terms of sensitivity, a smaller sensitivity value indicates higher performance.

  Example 1 shows the best results in the color misregistration variation (A) and the color misregistration sensitivity (B). In the variation of banding in (C) and the sensitivity of banding in (D), Example 2 shows the best results, but the results are sufficiently good in Example 1, and the effectiveness of the present invention is improved. Sex can be confirmed.

  The rotating body drive device according to the present invention is not limited in size, such as banding or color misregistration, without increasing the size of the device due to an increase in the arrangement space by the large-diameter flywheel and increasing the manufacturing cost due to the complexity of the large output motor and configuration. Rotating body drive device having a flywheel that has the effect of suppressing fluctuations in the rotational speed of the rotating body that causes problems, and that suppresses fluctuations in the rotational speed of the rotating body. This is useful for devices that require high-precision rotation and low noise using a stepping motor. The image recording apparatus according to the present invention includes an image recording apparatus having a driving mechanism such as a photosensitive drum as a rotating body and a support roller around which an intermediate transfer belt is wound, such as a printer, a copying machine, a facsimile machine, and a multifunction machine. It is useful as such.

Schematic sectional view showing an image forming apparatus to which the present invention is applied The perspective view which shows the drive device of the photosensitive drum shown in FIG. The front view which shows the principal part of the drive device of the photosensitive drum shown in FIG. Sectional drawing which shows the principal part of the drive device of the photosensitive drum shown in FIG. FIG. 4 is a perspective view schematically showing a drive device for the photosensitive drum shown in FIG. Sectional drawing which shows typically the drive device of the photosensitive drum shown in FIG. The typical perspective view which shows another example of the drive device of the rotary body by this invention. Sectional drawing which shows the modification of the drive device of the photosensitive drum shown in FIG. Typical sectional drawing which shows another example of the drive device of the rotary body by this invention Typical sectional drawing which shows another example of the drive device of the rotary body by this invention Typical sectional drawing which shows another example of the drive device of the rotary body by this invention The figure which shows the experimental result of the drive device of the rotary body by this invention

Explanation of symbols

11a to 11d Process units 17a to 17d Photosensitive drum 20 Process cartridge 21 Intermediate transfer belts 23 and 24 Support rollers 34, 38 and 104 Motors 35a to 35d and 106 Gears (rotational transmission elements)
41 · 102 Flywheel 42 Support shaft 43 · 101 Connecting shaft (elastic cylindrical part)
51 mounting portion 52/103 input side joint portion 53 joint member 54/107 output side joint portion 71 bearing boss 73 support shaft 79 screw 121 rotation transmission member 122 gear portion (rotation transmission element)
123 Connection shaft portion 125 Output side joint portion 126 Bearing boss 127 Support shaft 131/151/171 Elastic cylindrical portion 132 Connection shaft 133/153/174 Rotation shaft 134 Gear portion (rotation transmission element)
157/175 Gear 152/172 Holding member 173 Output shaft

Claims (9)

A motor as a drive source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor;
On the power transmission path for transmitting the driving force of the motor to the rotating body, a connecting shaft having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity is provided. A drive device for a rotating body, wherein the flywheel is mounted. In order to transmit the driving force of the motor to the connecting shaft, it further includes a rotational transmission element disposed coaxially with the connecting shaft;
2. The drive device for a rotating body according to claim 1, wherein the rotation transmission element and the connecting shaft are formed separately from each other and fastened to each other by a screw screwed in an axial direction. In order to transmit the driving force of the motor to the connecting shaft, it further includes a rotational transmission element disposed coaxially with the connecting shaft;
2. The rotating body drive device according to claim 1, wherein the rotary transmission element and the connecting shaft are integrally formed of a synthetic resin material.   2. The rotating body drive device according to claim 1, wherein the connecting shaft includes a joint in which a joint member provided on the shaft on the rotating body side is detachably fitted in an axial direction. A motor as a drive source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor;
On the power transmission path for transmitting the driving force of the motor to the rotating body, there is provided a connecting shaft having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity. A drive device for a rotating body, which is disposed on the input side of a rotating shaft to which the flywheel is attached. A motor as a drive source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor;
The flywheel is held by a holding member having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity, and the holding member transmits a driving force of the motor to the rotating body. A rotating body driving device characterized in that it is mounted on a rotating shaft on a power transmission path, and is coupled to the rotating shaft so as not to be relatively rotatable at a position spaced from the mounting position of the flywheel in the axial direction. A motor as a drive source for driving the rotating body, and a flywheel for suppressing fluctuations in the rotational speed of the rotating body driven by the motor;
The flywheel is held by a holding member having an elastic cylindrical portion formed hollow by a synthetic resin material having a required spring rigidity, the holding member is externally mounted on the output shaft of the motor, and the output A drive device for a rotating body, characterized in that it is coupled so as not to rotate relative to a shaft at a position spaced in the axial direction from the mounting position of the flywheel.   The drive device for a rotating body according to any one of claims 1 to 7, wherein the synthetic resin material forming the elastic cylindrical portion is polyacetal.   An image recording apparatus comprising the rotating body drive device according to claim 1.

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