JP2006002826A - Driving transmission device and image forming device provided with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving transmission device and an image forming device provided with it capable of preventing transmission of vibration caused in meshing to a rotary body for forming image of a driven shaft, coping with a case where a mounting position in the axial direction of a gear is changed due to part dimensional tolerance, adjusting suppressing force in accordance with vibrating force generated at a meshing period, and improving quality of image and being suitable for miniaturization and reduction of weight. <P>SOLUTION: In this driving transmission device having a driving shaft 1 connected with a driving source like a motor, the driven shaft 3 for performing work, and a helical gear 4 as a transmission mechanism part for transmitting torque of the driving shaft 1 to the driven shaft 3, a damping rotary roller 5 turning together with rotation of a side face of the helical gear is pressed against the side face which is in the vicinity of a meshing part of the rotating driven side helical gear 4 and on which thrust force is applied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drive transmission device for accurately rotating a driven shaft in a mechanism system including a drive shaft, a driven shaft, and a transmission mechanism, and an image forming apparatus including the drive transmission device.

Conventionally, for example, a notch is provided at the side end of a helical gear, and a flywheel is provided so as to face the helical gear that absorbs vibration during meshing and the side of the driven gear. 2. Description of the Related Art A drive transmission device is known in which a flywheel is rotated together with a driven gear at a constant speed while preventing rotation (see, for example, Patent Documents 1 and 2).
In Patent Document 1, by providing a notch at the gear side surface end portion, the tooth surface strength and tooth surface accuracy of the peripheral portion thereof are lowered. In particular, when the gear is molded of resin, stress concentrates on the notch, and there is a possibility that the gear teeth in the peripheral part may be damaged by the load torque. Moreover, there is a concern about an increase in vibration due to a decrease in tooth trace error. For these reasons, it is not suitable for the drive transmission device.
In the case of Patent Document 2, it is a method of adding a flywheel. However, since the flywheel is incorporated, the product becomes heavier, and especially in the case of a color machine, a flywheel is attached to each of the four driven gears. The above problem becomes prominent. In addition, it is not suitable for miniaturization.
Japanese Utility Model Publication No. 6-28407 JP2003-206993A

However, when such a drive transmission device is used in an image forming apparatus, the influence of a gear transmission mechanism system in an image device is highly related to density unevenness (banding) in a filled image, and therefore vibration during meshing is generated. It must not be transmitted to the rotating body for image formation of the driven shaft.
Accordingly, an object of the present invention is to prevent the vibration at the time of meshing from being transmitted to the rotating body for image formation of the driven shaft in consideration of the above-mentioned situation, and the axial mounting position of the gear varies depending on the component dimensional tolerance. A drive transmission device suitable for small size and light weight and an image forming apparatus equipped with the drive transmission device can be provided that can control the deterrence force according to the magnitude of the excitation force generated in the meshing cycle. There is.

In order to solve the above-mentioned problem, the invention according to claim 1 is a drive transmission device having a drive gear that is rotationally driven by a drive source, and a helical gear that meshes with the drive gear and is driven to rotate. The present invention is characterized in that a vibration-suppressing rotary roller is pressed against a side portion of the helical gear, where a thrust force is applied in the vicinity of the meshing portion with the drive gear.
According to a second aspect of the present invention, in the first aspect, an elastic spring is provided to press the rotating roller against a side surface to which a thrust force is applied in the vicinity of the meshing portion of the helical gear.
According to a third aspect of the present invention, in the first or second aspect, the rotating roller is an elastic roller configured to generate a predetermined pressing force in advance.
According to a fourth aspect of the present invention, in the first, second, or third aspect, the rotating roller is brought into contact with a side surface near the outer periphery of the helical gear.
A fifth aspect of the present invention is characterized in that, in the first, second, third, or fourth aspect, unevenness corresponding to the meshing frequency is provided on the side surface of the driven gear that the rotating roller rotates.
According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the rotating roller is brought into contact with both side surfaces of the driven gear.
A seventh aspect of the present invention includes the contacting / separating mechanism according to any one of the first to sixth aspects, wherein the rotating roller moves away from the side surface of the helical gear when the drive gear is started, and advances and retreats so that the rotating roller contacts and rotates at a constant speed. It is characterized by.
The invention of claim 8 is characterized in that, in any of claims 1 to 7, the rotating roller applies a constant load to the helical gear.
A ninth aspect of the invention is characterized in that, in the first to eighth aspects, the rotating roller has a truncated cone shape, and a radius corresponding to the outer peripheral side of the driven gear is increased.
According to a tenth aspect of the present invention, there is provided an image carrier that forms an electrostatic latent image on the surface and rotates in the circumferential direction, a developing means that visualizes the electrostatic latent image on the image carrier, and a visualization An image forming apparatus having a transfer unit that transfers a toner image to a recording material and a fixing unit that fixes the toner image on the transferred recording material. An image forming apparatus having a drive transmission device configured to press a rotating roller for vibration suppression along with the rotation of a side surface against a side surface to which a thrust force is applied in the vicinity of the meshing portion.

According to the present invention, application to a photoconductor drum drive system of a copying machine or a printer is applied to a wide range of fields in which a driven shaft is accurately operated by suppressing rotation unevenness of a meshing cycle generated in a gear transmission mechanism. it can.
In addition, the configuration is such that the rotating roller for vibration suppression that rotates with the side surface is pressed against the side surface to which the thrust force in the vicinity of the meshing portion of the rotating driven side helical gear is pressed, so that it varies depending on the magnitude of the load torque. When the thrust force is applied to the large-diameter gear tooth portion, the elastic deformation is reduced, and the vibration in the thrust direction of the tooth side surface in the meshing period is suppressed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the configuration of a drive transmission device according to the present invention. FIG. 2 is a right side view of the configuration of FIG. FIG. 3 is a schematic diagram showing the thrust force generated in the driven gear of FIG. FIG. 4 is a schematic view showing suppression of thrust force by a vibration-suppressing rotary roller.
1 to 4, a shaft center portion of a drive gear 2 is fixed to a drive shaft 1 connected to a drive source (not shown) such as a motor. The driven shaft 3 that performs the work is provided with a driven gear 4 that is a helical gear as a transmission mechanism that transmits the torque of the drive shaft 1 to the driven shaft 3.
The drive gear 2 and the driven gear 4 are engaged with each other. As can be seen from FIGS. 1 and 2, a vibration-reducing rotating roller 5 that rotates with the side surface rotation is pressed against the side surface to which the thrust force is applied in the vicinity of the meshing portion of the rotating helical gear 4 on the driven side. Provided.
The helical gear (in this case, the driven gear 4) is smoother in torque transmission in the rotational direction by increasing the number of meshed teeth compared to the spur gear, but the angle at which the tooth is tilted from the axial direction (torsion angle) A thrust force is generated according to β) (FIG. 3).
In particular, in the case of a large-diameter resin gear, the gear tooth surface is inclined due to the influence of this thrust force, and an error is generated from the normal tooth surface position. Further, although torque transmission is smooth, vibration occurs at the meshing cycle, and the tooth surface having a large diameter vibrates in the axial direction (thrust direction).
As a means for suppressing this, the circumferential surface of the rotating roller 5 for vibration suppression that rotates together with the side surface rotation is provided on the side surface to which the thrust force is applied in the vicinity of the meshing portion of the rotating helical gear 4 on the driven side as described above. The structure is to be pressed.
The vibration-suppressing rotating roller 5 suppresses elastic deformation when a thrust force that changes according to the magnitude of the load torque is applied to the large-diameter gear tooth portion, and reduces the error of the tooth surface position (FIG. 4).
Further, the tooth surface side surface vibrates in the thrust direction in synchronism with the meshing cycle, and has two functions of suppressing this by the damping roller 5 for vibration suppression. As a result, the tooth surface position approaches the normal position, the rotation unevenness is reduced, and the thrust vibration can be directly suppressed, so that the effect is doubled.

FIG. 5 is a schematic view showing a first embodiment of an elastic support mechanism for a vibration-suppressing rotary roller. FIG. 6 is a schematic view showing a second embodiment of the elastic support mechanism of the vibration-rotating rotary roller. The vibration-suppressing rotating roller 5 that suppresses meshing vibration and thrust deformation is configured to be pressed by an elastic spring of a roller support mechanism.
As an elastic spring system, various elastic members such as a leaf spring 6 supported by the base portion 6a as shown in FIG. 5 or a spring (coil spring) 7 supported by the base portion 7a as shown in FIG. 6 can be applied. With these elastic springs, even when the position of the side surface of the driven gear 4 is changed due to variations in the component dimensions, it is possible to appropriately press the rotating roller 5 for vibration suppression.
Even if the thrust vibration increases, the restoring force of the elastic bodies 6 and 7 increases accordingly, so that the thrust vibration can be reduced. Therefore, the meshing vibration of the helical gear 4 can be efficiently reduced.
FIG. 7 is a schematic view showing a first modification of the vibration-suppressing rotary roller. In FIG. 7, the rotating roller for vibration suppression that suppresses meshing vibration and thrust deformation is an elastic roller 5a. In this case, it is set as the structure which becomes a fixed press beforehand.
As the elastic body roller 5a, a bearing in which rubber or urethane is arranged on the outer peripheral portion as shown in the figure, or a resin-molded one can be applied. Even when the position of the side surface of the driven gear changes due to the variation in the component dimensions, the elastic roller 5a can appropriately press the rotating roller for vibration suppression. Even if the thrust vibration is increased, the restoring force of the elastic body is increased accordingly, so that the thrust vibration can be reduced.

FIG. 8 is a schematic view showing the first embodiment of the mounting position of the vibration-suppressing rotary roller. FIG. 9 is a schematic view showing a second embodiment of the mounting position of the vibration-suppressing rotary roller. The meshing vibration and the thrust deformation increase as the distance from the rotating shaft 3 increases. When the thrust force Fs is applied to the tooth surface having the radius r, the roller pressing force is about Fs when the damping rotary roller 5 is arranged near r (FIG. 8).
However, when the vibration-suppressing rotating roller 5 is provided at the r / 2 position (FIG. 8), the roller pressing force is required to be 2 Fs, and a load (life, support mechanism) is applied to the rotating roller surface. In view of this, a vibration-reducing rotating roller 5 is disposed at a point (outer peripheral side) where vibration and deformation are large to reduce vibration and deformation.
As changes (vibrations and deformations) become larger, it is easier to suppress and the effect is great. Although the peripheral speed increases as it goes to the outer peripheral side, the rotating roller system is more advantageous than the sliding contact system that does not rotate, and it can cope with high-speed operation.
FIG. 10 is a schematic diagram showing the uneven processing applied to the side surface of the helical gear. The meshing vibration of the helical gear (driven gear) 4 is generated at a frequency corresponding to the rotational speed × the number of teeth. Due to this vibration, the outer periphery of the helical gear vibrates in the thrust direction.
Therefore, as shown in FIG. 10, the side surface of the toothed gear is processed with a constant pitch in the circumferential direction so that the phase is reversed at the same frequency as this vibration. As a result, the vibration-suppressing rotating roller 5 is displaced in the thrust direction when moving on the uneven surface, and the product of the displacement amount and the elastic member rigidity value acts in a direction to cancel the meshing vibration, thereby reducing the meshing vibration. it can.
FIG. 11 is a schematic diagram showing an embodiment in which rotating rollers for vibration suppression are provided on both sides of the driven gear. When the rotation direction includes forward rotation and reverse rotation, the thrust force is in two directions as shown in FIG. Therefore, the vibration-suppressing rotating rollers 5 supported by the fixed portion 5b are arranged on both sides of the side surface of the driven gear 4 so as to be able to cope with either direction.
As a result, even if the rotation direction changes, it is possible to provide a drive system that can transmit rotation with high accuracy even when one of the vibration-suppressing rotating rollers works to suppress vibration and rotates forward and reverse. it can.

FIG. 12 is a schematic diagram showing the contact / separation relationship between the vibration-suppressing rotary roller and the driven gear with respect to the rotational speed and time of the driven gear. FIG. 13 is a schematic diagram showing the contact / separation relationship between the vibration-suppressing rotary roller and the driven gear with respect to the rotational speed and time of the vibration-suppressing rotary roller.
When the drive system is started, an inertia load corresponding to the start acceleration is added to the drive motor in addition to the steady load torque. In particular, in the case of starting in a short time, the starting torque becomes large, and if the load torque of the damping roller 5 is added to this, it is necessary to increase the output and capacity of the drive motor.
Therefore, in order to reduce the burden on the motor at the time of starting, the vibration-suppressing rotating roller 5 is separated from the side surface of the driven gear 4 at the time of starting, and is brought into contact with the rotating gear 5 after reaching a steady speed.
For this purpose, a contact / separation mechanism for moving the rotating roller 5 back and forth with respect to the side surface of the toothed gear is provided. The contact / separation mechanism is driven by, for example, a solenoid.
When the driven gear is started as shown in FIG. 13 (time interval 0 to t1), the rotating roller 5 for vibration control is separated from the driven gear 4, so the rotating roller 5 does not rotate. Thereafter, the vibration-suppressing rotating roller 5 and the driven gear 4 come into contact with each other after t1 when the speed reaches a constant speed, and perform functions such as vibration suppression.
As a result, the burden on the motor at the time of startup is reduced, and vibration can be suppressed by contact at a constant speed. It is possible to provide a drive system that is suitable for energy saving without reducing the burden on the motor at the time of start-up and without using a motor with a larger capacity than necessary.
Generally, a gear is used with a backlash in order to make the rotation smooth, taking into account the dimensional tolerance between shafts, the thermal expansion of the gear, and the like. Under such circumstances, when a disturbance torque is applied, the tooth surfaces jump and separate, and rotation unevenness occurs due to the backlash gap.

FIG. 14 is a schematic view showing an embodiment for explaining a load caused by a vibration-suppressing rotary roller. Therefore, a constant load torque is applied from the vibration-suppressing rotating roller 5 side so that the tooth surfaces are not separated from each other. As shown in FIG. 14, the sliding friction between the fixed shaft 9 that supports the rotating roller 5 and the inner peripheral surface of the damping roller 5 is used. In this example, the shaft hole 5 </ b> A of the rotating roller 5 has a larger diameter than the diameter of the fixed shaft 9.
The load torque applied from the rotating roller 5 can be adjusted by the shaft diameter of the fixed shaft 9, the width of the sliding bearing, and the pressing force. As a result, the tooth surfaces always come into contact with each other without the tooth surfaces jumping due to disturbance torque, and high-accuracy rotation can be provided.
FIG. 15 is a schematic view showing an embodiment in which the damping roller is a truncated cone roller. In FIG. 15, the vibration-rotating rotary roller is a truncated cone roller 5 ′, and the radius rb corresponding to the outer peripheral side of the driven gear 4 is made larger than the other radius ra (FIG. 15).
When the rotating roller 5 has a cylindrical shape, there is no problem if the thickness is small, but as the thickness increases, a speed difference occurs between the outer peripheral side (r2) and the inner peripheral side (r1). If it is used for a long period of time, the shape of the rotating roller may change due to wear and may not function.
Therefore, the rotating roller 5 is formed in a truncated cone shape and has a shape corresponding to the inner peripheral side and the outer peripheral side (r1 / r2 = ra / rb). As a result, no speed difference occurs, so that the shape of the rotating roller 5 can be maintained with the same amount of wear even when used for a long period of time, and can work stably.

FIG. 16 is a schematic view showing an embodiment of an image forming apparatus provided with a drive transmission device according to the present invention. In FIG. 16, it is assumed that a rotating body for image formation is attached to the driven shaft 3.
First, the outline of the image forming apparatus will be described with reference to FIG. FIG. 16 is a longitudinal front view schematically showing the internal structure of the image forming apparatus. A paper feed cassette 11 is detachably mounted on one side of the image forming apparatus main body 10 and a paper discharge port 12 is provided on the other side of the main body. It has been.
A photosensitive member 14 is rotatably provided above a paper conveyance path 13 from the paper feed cassette 11 to the paper discharge port 12, and a charger 15, an exposure device 16, and a developing device 17 as process units are provided around the photosensitive member 14. Are arranged. Further, a transfer device 18, a cleaning device 19, a static eliminator 20, and the like are arranged on the outer periphery of the photosensitive member 14.
Further, a paper feed roller 21, a registration roller 22, a fixing roller 25 having a heat roller 23 and a press roller 24, and a paper discharge roller 26 are arranged from upstream to downstream along the paper transport path 13.
With such a configuration, the surface of the photoconductor 14 is charged by the charger 15, and an electrostatic latent image is formed by scanning the laser beam from the exposure device 16 in that portion. Thereafter, the electrostatic image is developed as a toner image by the developing device by the rotation of the photosensitive member (photosensitive drum) 14.
On the other hand, the paper in the paper feeding cassette 11 is pulled out to the registration roller 22 by the paper feeding roller 21, and the paper is fed to the lower part of the photosensitive drum by the registration roller 22 that rotates in synchronization with the rotational movement of the photosensitive drum 14.
The toner image on the photoreceptor 14 is transferred to a sheet by the transfer unit 18, and the transferred image on the sheet is fixed when the sheet passes through the fixing unit 25. Thereafter, the fixed sheet is discharged from the apparatus discharge port 12 by a discharge roller 26.
In such a product, the constant speed characteristic of the shaft of the photosensitive drum 14 directly affects the image quality. When the motor torque is transmitted to the shaft of the photosensitive drum 14 by a gear and driven, the torque of the motor itself It is important to reduce torque vibration by gear meshing as well as to suppress fluctuations.

The configuration is such that the vibration-suppressing rotating roller 5 that rotates with the side surface is pressed against the side surface to which the thrust force in the vicinity of the meshing portion of the driven side helical gear 4 that drives the image carrier (photosensitive drum) 14 is applied. Thus, there is a function of reducing elastic deformation when a thrust force that varies depending on the magnitude of the load torque is applied to the large-diameter gear tooth portion, and suppressing vibration of the tooth surface side surface in the meshing cycle in the thrust direction.
This vibration-suppressing rotary roller (1) suppresses elastic deformation when a thrust force that changes depending on the magnitude of the load torque is applied to the large-diameter gear tooth portion, and reduces errors in the tooth surface position. Further, (2) the tooth side surface vibrates in the thrust direction at the meshing cycle, and this has two functions of suppressing this by the vibration-suppressing rotating roller.
As a result, the tooth surface position approaches the normal position, the rotation unevenness is reduced, and the thrust vibration can be directly suppressed, so that the effect is doubled.
Particularly, the meshing frequency (number of teeth) of the gear is a frequency band that is conspicuous for human eyes as banding with uneven density. By suppressing the vibration at this frequency, the image quality can be improved.
In addition, since the rotating roller can be configured with a smaller size and lighter weight than a flywheel or the like, the drive mechanism can be saved in space, contributing to the downsizing of the product.
Up to this point, the case where the present invention is applied to the photosensitive drum has been described. However, it can be applied to the transmission mechanism portion of the driving roller for driving the photosensitive belt and the transmission mechanism portion of the driving roller in the intermediate transfer belt method. There is no.

Schematic which shows embodiment of the structure of the drive transmission device by this invention. The right view of the structure of FIG. Schematic which shows the thrust force which generate | occur | produces in the driven gear of FIG. Schematic which shows suppression of the thrust force by the rotating roller for vibration suppression. Schematic which shows 1st Embodiment of the elastic support mechanism of the rotating roller for vibration suppression. Schematic which shows 2nd Embodiment of the elastic support mechanism of the rotating roller for vibration suppression. Schematic which shows the 1st modification of the rotating roller for vibration suppression. Schematic which shows 1st Embodiment of the attachment position of the rotating roller for vibration suppression. Schematic which shows 2nd Embodiment of the attachment position of the rotating roller for vibration suppression. Schematic which shows the uneven | corrugated process given to the helical gear side surface. Schematic which shows embodiment which provides the rotating roller for vibration suppression on the both sides of a driven gear. Schematic which shows the relationship between the rotation speed of a driven gear, and time with the graph of the relationship between the rotation roller for vibration suppression, and a driven gear. Schematic which shows the relationship of the separation / rotation of the rotation roller for vibration suppression and a driven gear with a graph regarding the rotational speed and time of the rotation roller for vibration suppression. Schematic which shows embodiment which demonstrates the load by the rotating roller for vibration suppression. Schematic which shows embodiment which made the rotation roller for vibration suppression into the roller of truncated cone shape. 1 is a schematic diagram showing an embodiment of an image forming apparatus including a drive transmission device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive shaft, 2 Drive gear, 3 Drive shaft, 4 Drive gear (Transmission mechanism part, helical gear), Damping rotary roller, 5a Elastic roller, 5b Roller support mechanism (fixed part), 5 ' Frustoconical roller, 6 elastic spring (plate spring), 6a roller support mechanism (fixed part), 7 elastic spring (coil spring), 7a roller support mechanism (fixed part), 8 irregularities, 9 fixed shaft, 10 image forming apparatus main body , 14 Image bearing member (photosensitive member, photosensitive drum), 17 developing means (developing device), 18 transferring means (transfer device),
25 Fixing means (fixing device)

Claims (10)

  In a drive transmission device having a drive gear that is rotationally driven by a drive source, and a helical gear that meshes with the drive gear and rotates following the drive gear, the side surface of the helical gear near the meshing portion with the drive gear A drive transmission device characterized in that a vibration-suppressing rotating roller is pressed against a portion to which a thrust force is applied and is rotated.   2. The drive transmission device according to claim 1, further comprising an elastic spring for pressing the rotating roller against a side surface to which a thrust force is applied in the vicinity of the meshing portion of the helical gear.   The drive transmission device according to claim 1, wherein the rotating roller is an elastic roller configured to generate a predetermined pressing force in advance.   4. The drive transmission device according to claim 1, wherein the rotating roller is brought into contact with a side surface of the helical gear near the outer periphery.   5. The drive transmission device according to claim 1, wherein unevenness corresponding to a meshing frequency is provided on a side surface of the driven gear which the rotating roller rotates.   The drive transmission device according to any one of claims 1 to 5, wherein the rotating roller is brought into contact with both side surfaces of the driven gear.   7. The contact mechanism according to claim 1, further comprising a contact / separation mechanism configured to move away from the side surface of the helical gear when the drive gear is started, and to advance and retract so as to contact and rotate at a constant speed. The drive transmission device according to item.   The drive transmission device according to any one of claims 1 to 7, wherein the rotating roller is configured to apply a constant load to the helical gear.   The drive transmission device according to any one of claims 1 to 8, wherein the rotating roller has a truncated cone shape and has a larger radius corresponding to the outer peripheral side of the driven gear. An image carrier that forms an electrostatic latent image on the surface and rotates in the circumferential direction, a developing unit that visualizes the electrostatic latent image on the image carrier, and a toner image that is visualized is transferred to a recording material And a fixing unit that fixes the toner image on the recording material to be transferred. A side surface to which a thrust force is applied in the vicinity of the meshing portion of the driven side helical gear that drives the image carrier. An image forming apparatus comprising a drive transmission device configured to press against a vibration-suppressing rotating roller that rotates with the side surface.

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