JP2001153133A - Drive transmission device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive transmission device smoothly rotating a pbotoreceptor drum by increasing inertia moment without extensively changing the diameter or weight of a flywheel, and to provide an image forming device which does not increase a load to a driving mechanism. SOLUTION: This drive transmission device 10 has a flywheel 20 for eliminating the rotational unevenness of a rotation shaft, wherein the flywheel 20 has a disc shape and is hollowed on an inner side thereof. An image forming device is provided with the drive transmission device 10. Therefore, an inertial moment 1 can be easily fine-adjusted while attaching the flywheel 20 without burdensome operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive transmission device for an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and more particularly, to a flywheel for reducing rotation speed unevenness of a rotation shaft for rotating an image carrier. More particularly, the present invention relates to an image forming apparatus including the drive transmission device.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system, the surface of an image carrier such as a photosensitive drum is uniformly charged by a charging device, and a latent image corresponding to an image to be formed is charged by a laser beam. Writing is performed on the surface of the formed image carrier, and toner is transferred from the developing device to the latent image to visualize the latent image. Then, the toner image is directly or indirectly transferred onto a recording member such as paper or an OHP sheet. The diameter of the laser beam is, for example, 40 to
The laser beam scans on the image carrier to form a latent image. In this case, if the image carrier travels at a constant speed, the interval between the writing lines for the latent image is constant. However, if the traveling speed of the image carrier becomes unstable due to, for example, vibration, the interval between the writing lines for the latent image becomes constant. Sparse and dense. As a result, density unevenness also occurs in the toner image,
Image quality is degraded. Further, in the color image forming apparatus, a color image is formed by laminating toner images of a plurality of colors. However, if there is uneven density in each color toner image, the color image will not have a desired color tone. As a factor of such instability of the rotation speed of the image carrier, there is periodic vibration due to an error in the mounting accuracy of the rotation center shaft. In addition, particularly in an image forming apparatus, a movable developing device, a transfer device, and a cleaning blade may be provided. However, when these are brought into contact with and retracted from the image carrier, instantaneous deceleration and acceleration of the image carrier are performed. Trigger. Further, the fluctuation of the speed of the conveying roller of the sheet is transmitted through the sheet on which the image is formed, or the fluctuation of the speed of the developing roller of the developing device that is in contact with the image carrier is also transmitted. Occurs. Further, when the image carrier is driven by a gear, there is also a short-period vibration due to an instantaneous change in rotational speed due to a backlash of the gear. Therefore, in order to stabilize the speed of the image carrier, generally, a flywheel is attached to the rotation axis of the image carrier to increase the moment of inertia and smooth the rotational speed of the image carrier. Is being done.

In order to smooth the rotation speed of the image carrier, for example, Japanese Patent Application Laid-Open No. H11-231723 has proposed a rotation stabilizing device for stabilizing the rotation of a photosensitive drum. . This rotation stabilizing device includes a flywheel attached to a rotating shaft of a photosensitive drum, a plurality of movable bodies slidably supported in a radial direction of the flywheel, and a movable body in a direction of a center axis of the flywheel. A spring for biasing the movable body is displaced by a biasing force of the spring and centrifugal force due to rotation to vary the moment of inertia.

[0004]

However, in the rotation stabilizing device proposed in Japanese Patent Application Laid-Open No. 11-231723, when an image carrier such as a photosensitive drum is rotated by a gear or the like, the rotation of the image carrier is reduced. There is a problem that the movable body fluctuates every time a short period of vibration occurs due to vibrations caused by a motor or the like as a driving source or gear backlash, and amplifies the vibration of the image carrier. Further, there is a problem that the structure of the rotation stabilizing device becomes complicated, and the cost of the image forming apparatus increases. Further, when the weight of the flywheel or the like increases, power consumption for image formation increases, and the load on the photosensitive drum increases, thereby lowering the durability of the drive mechanism of the image forming apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to increase the moment of inertia of a flywheel without significantly changing the diameter and weight of the flywheel. An object of the present invention is to provide a drive transmission device for smoothing the rotation, and to provide an image forming apparatus that does not increase the load on the drive mechanism. It is still another object of the present invention to provide a drive transmission device or the like that can adjust the moment of inertia while the flywheel is mounted, and can rotate and drive the image carrier with an optimum moment of inertia. Another object of the present invention is to provide a drive transmission device and the like that can easily change the position of a movable member on a flywheel. Another object of the present invention is to provide a drive transmission device and the like in which a movable member for adjusting the moment of inertia is fixed without moving during rotation, and the photosensitive drum is rotated stably.

[0006]

According to a first aspect of the present invention, there is provided a drive transmission device having a flywheel for eliminating rotation unevenness of a rotating shaft, wherein the flywheel is a disk. It is a drive transmission device which has a shape and has a lightened inside. The invention according to claim 2 is the drive transmission device according to claim 1,
The flywheel is a drive transmission device provided with a movable member inside. The invention according to claim 3 is the drive transmission device according to claim 2, wherein the flywheel is a drive transmission device in which a movable member provided inside is fixed by a spring pin. The invention according to claim 4 is the drive transmission device according to claim 2, wherein the flywheel is a drive transmission device in which a movable member provided inside is fixed by a spring.

According to a fifth aspect of the present invention, there is provided an image carrier which forms an electrostatic latent image on a surface thereof and is rotated in a circumferential direction, and a developing means for visualizing the electrostatic latent image on the image carrier. In an image forming apparatus including a transfer unit that transfers a toner image to be visualized to a recording material and a fixing unit that fixes the toner image on the recording material to be transferred, a rotation shaft that rotationally moves an image carrier is An image forming apparatus, comprising: a flywheel having a disc-like shape and hollowing out the inside. According to a sixth aspect of the present invention, in the image forming apparatus of the fifth aspect, the flywheel is provided with a movable member inside. According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the flywheel is an image forming apparatus in which a movable member provided inside is fixed by a spring pin. According to an eighth aspect of the present invention, in the image forming apparatus of the sixth aspect, the flywheel is an image forming apparatus in which a movable member provided inside is fixed by a spring.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a configuration diagram schematically showing an image forming apparatus according to an embodiment of the present invention. The main body of the image forming apparatus 1 includes an optical writing unit 6, a paper supply unit 8, a paper supply roller 81, a registration roller 82, a transfer roller 7, a fixing unit 3, and a process unit 2. The process unit 2 houses an image bearing member (hereinafter, referred to as a “photosensitive drum”) 5 and a photosensitive drum 5 rotatably supported therein and toner, and a developing device rotatably supports the developing roller 41. The unit 4 and a cleaning device that cleans the toner on the photosensitive drum 5 and arranges a waste toner storage unit that stores the cleaned waste toner are integrally formed in the process unit 2 frame.
The photoconductor drum 5 and the developing unit 4 are connected by a connecting member, and are supported rotatably with the connecting portion as a fulcrum. Image formation by the image forming apparatus 1 is performed as follows. When the process unit 2 is set on the main body of the image forming apparatus 1 and the cover member is closed, the image forming apparatus 1 becomes operable. First, prior to image formation, the surface of the photosensitive drum 5 in the process unit 2 is uniformly charged by the charging roller 9.

Subsequently, image light obtained by light irradiation from a light source (not shown) is read by a CCD sensor. In the optical writing unit 6 fixedly supported by the image forming apparatus main body 1, light emitted from a laser light source (not shown) in accordance with image information is scanned by a polygon mirror (not shown) based on the information of the CCD, and a lens and a reflection mirror are provided. A light image based on the image information is radiated to the photosensitive drum 5 via the, and a latent image is formed on the surface of the photosensitive drum 5. At this time, the light from the laser light source is linearly written in the main scanning direction while moving at a fixed time in the sub-scanning direction with respect to the photosensitive drum 5, but if the rotation of the photosensitive drum is not smooth, Unevenness occurs in the latent image in any direction. In particular, in a full-color digital image forming apparatus, when scanning unevenness occurs in each color by a laser beam, an image having a color shift or an uneven color tone is formed. The latent image formed on the surface of the photosensitive drum 5 is conveyed to a developing area facing the developing roller 41 as the photosensitive drum 5 rotates. In the developing unit 4, the toner contained in the toner hopper is sent to the developing roller 41 side by the toner sending member, and is pumped to the surface of the developing roller 41. The toner pumped to the surface of the developing roller 41 is conveyed by the rotation of the developing roller 41, and is regulated to a predetermined layer thickness when passing the position of the developing blade, so that a thin toner layer is formed. The thin toner layer is further transported to a development area facing the photoconductor drum 5, where the latent image is developed to form a toner image. On the other hand, transfer paper is pulled out one by one by a paper feed roller 81 from a paper feed tray 83 provided in the main body of the image forming apparatus 1, passes through a registration roller 82, and rotates downstream of the photosensitive drum 5 with respect to the development area. The toner image on the photosensitive drum 5 is transferred to the transfer paper, and further transferred to the fixing unit 3 where the toner image on the transfer paper is fixed. An image is formed.

Here, the drive transmission device 10 for rotating the photosensitive drum 5 will be described. FIG. 2 is a schematic diagram showing a configuration near a photosensitive drum of the drive transmission device according to one embodiment of the present invention. As shown in FIG.
Reference numeral 1 is fastened to the side plate 12 of the housing of the image forming apparatus by a screw. In the drive unit 11, drive is transmitted from the drive gear 14 attached to the motor 13 to the photosensitive drum 5 via the reduction gear 15 and the coupling gear 16 connected to the photosensitive drum 5. Here, the flywheel 20 is mounted on the photosensitive drum rotating shaft 17 via the wheel mounting flange 18. Here, a signal of a control unit (not shown) of the main body of the image forming apparatus 1 is transmitted to the motor 13, the motor 13 is driven, and the rotation is
The rotation of the photosensitive drum 5 is transmitted to the photosensitive drum rotating shaft 17 through the motor and the reduction gear 15 and the like, and the photosensitive drum 5 rotates in the circumferential direction. FIG.
1 is a schematic plan view and a side view showing a shape of a flywheel used in a drive transmission device according to an embodiment of the present invention. FIG. 4 is a schematic diagram for explaining the moment of inertia. Here, the moment of inertia I can be represented by the following equation.

(Equation 1) Equation 1 represents the moment of inertia of an object having a mass M that rotates around the center point O. Δm is the mass of a minute portion of the object, and the distance r is the distance between the minute portion Δm and the center point O. As the inertia moment I is larger, the state of the rotational motion is less likely to change. According to Equation 1, the larger the mass M of the object away from the center point, the larger the moment of inertia I. Therefore, in the form of the flywheel 20 of the present invention, as shown in FIG.
The weight of the part away from the center is increased by increasing the thickness of the outer part. As a result, the moment of inertia I applied to the rotating shaft is increased as compared with the case where the flywheel 20 having the same diameter and the same weight and having the same weight is used. , A larger moment of inertia I can be applied.

Therefore, in the drive transmission device according to the first aspect, the flywheel 20 as shown in FIG.
By mounting, the fluctuation of the rotation of the motor 13 and the fluctuation of the rotation of the photosensitive drum rotating shaft 17 due to the backlash of the gear transmitting the rotating force to the photosensitive drum rotating shaft 17 can be suppressed, and the rotation can be smoothed. it can. Further, in the image forming apparatus according to the fifth aspect, such a drive transmission device 10
, The developing unit 4 and the transfer roller 7
Prevents the instantaneous fluctuation of the speed of the photosensitive drum 5 caused to come into contact with and retreats from the photosensitive drum 5, and eliminates the density of the latent image formed by the irradiation of the laser beam, whereby a high-quality image can be obtained. .

(Second Embodiment) FIG. 5 is a schematic plan view showing a shape of a flywheel used for a drive transmission device according to an embodiment of the present invention. The flywheel 20 is composed of an inner portion 21 having a rib portion and a donut-shaped outer portion 22. A movable member 23 is arranged on the inner rib portion, and the movable member 23 moves in the direction of the arrow. Can be freely fixed using screws. Accordingly, even when it is necessary to apply an inertia moment I suitable for the rotation speed of the photosensitive drum 5 to the photosensitive drum rotating shaft 17, it is troublesome to change the number of flywheels 20. Without operating the flywheel 20, the photosensitive drum rotating shaft 1
7, the moment of inertia I can be easily adjusted. In the image forming apparatus according to the sixth aspect, by arranging such a drive transmission device 10, a high-quality image can be obtained. Furthermore, even when the photosensitive drums 5 of the same size are used, the movable member 23
Can be easily fine-tuned to the inertia moment I that is optimal for the image forming apparatus 1 having different image forming speeds.

(Third Embodiment) FIG. 6 is a schematic plan view showing the shape of a flywheel used in a drive transmission device according to a third embodiment of the present invention. A plurality of holes 25 for fixing the movable member 23 are formed along the rib portion of the inner portion 21 of the flywheel. At the positions of these holes 25, the movable member 23
Or the movable member 23 and the flywheel outer portion 22 are connected by two springs 26. Accordingly, the movable member 23 can be moved on the flywheel 20 without the need for a screw hole drilling operation for the flywheel 20 and a screw tightening operation when the position is changed, which occurs when a screw is used to change the position of the movable member 23. 23 can be easily changed. In the image forming apparatus according to the seventh and eighth aspects, by arranging such a drive transmission device 10, a high-quality image can be obtained. Further, since it is easy to adjust the moment of inertia I optimal for the image forming apparatus, a high-quality image can be obtained.

It should be noted that the drive transmission device of the present invention is not limited to the rotation of the photosensitive drum of the image forming apparatus of the electrophotographic type, but also the rotation drive device for scanning the optical system, and the recording of the transfer paper from the paper supply unit. It can be used for smoothing the rotation of a driving device for transporting a member.

[0015]

As described above, in the drive transmission device according to the first aspect, the moment of inertia applied to the rotating shaft is larger than when a flywheel having the same diameter and the same weight and a constant thickness is used. In addition, a large moment of inertia can be applied to the rotating shaft of the drum without largely changing the diameter and weight of the flywheel. Further, in the drive transmission device according to the second aspect, when the rotational speed of the photosensitive drum changes and it is necessary to apply an inertia moment suitable for the change to the drum shaft, a troublesome operation such as changing the number of flywheels is performed. Therefore, fine adjustment of the moment of inertia can be easily performed while the flywheel is mounted. In the drive transmission device according to the third aspect, a flywheel can be formed without a trouble of screw hole processing on a flywheel and screw tightening work at the time of position change, which occurs when a screw is used to change the position of the movable member. The position of the movable member on the wheel can be easily changed. In the drive transmission device according to the fourth aspect, the movable member can be fixed without rattling during rotation of the photoconductor drum, and stable rotation of the photoconductor drum can be realized.

Further, in the image forming apparatus according to the present invention, a high-quality image can be obtained by preventing the fluctuation of the speed of the photosensitive drum and eliminating the density of the latent image formed by the irradiation of the laser beam. Can be. Further, in the image forming apparatus according to the present invention, fine adjustment can be easily made to an inertia moment optimal for an image forming apparatus having different image forming speeds by using photosensitive drums of the same size. In the image forming apparatus according to the seventh and eighth aspects, it is easy to adjust the moment of inertia optimal for the image forming apparatus, so that a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically illustrating an image forming apparatus according to an embodiment of the invention.

FIG. 2 is a schematic diagram showing a configuration near a photosensitive drum of a drive transmission device according to an embodiment of the present invention.

FIG. 3 is a schematic plan view and a side view showing a shape of a flywheel used in the drive transmission device according to the embodiment of the first aspect of the present invention.

FIG. 4 is a schematic diagram for explaining a moment of inertia.

FIG. 5 is a schematic plan view showing a shape of a flywheel used in a drive transmission device according to an embodiment of the present invention.

FIG. 6 is a schematic plan view showing a shape of a flywheel used in a drive transmission device according to an embodiment of the invention described in claims 3 and 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Process unit 3 Fixing unit 4 Developing unit 41 Developing roller 5 Photoreceptor drum 6 Optical writing unit 7 Transfer roller 8 Feeding unit 81 Feeding roller 82 Registration roller 83 Feeding tray 9 Charging roller 10 Drive transmission device 11 Drive unit 12 Image forming apparatus housing side plate 13 Motor 14 Drive gear 15 Reduction gear 16 Coupling gear 17 Photoreceptor drum rotating shaft 18 Wheel mounting flange 20 Flywheel 21 Flywheel inner part 22 Flywheel outer part 23 Movable member 24 Spring Pin 25 Hole 26 Spring

Claims (8)

[Claims] 1. A drive transmission device having a flywheel for eliminating rotation unevenness of a rotating shaft, wherein the flywheel has a disk-like shape and the inside is lightened. . 2. The drive transmission device according to claim 1, wherein the flywheel is provided with a movable member inside. 3. The drive transmission device according to claim 2, wherein the flywheel has a movable member provided inside fixed by a spring pin. 4. The drive transmission device according to claim 2, wherein the flywheel has a movable member provided inside fixed by a spring. 5. An image carrier that forms an electrostatic latent image on its surface and rotates in a circumferential direction, a developing unit that visualizes the electrostatic latent image on the image carrier, and a toner that is visualized In an image forming apparatus having a transfer unit for transferring an image to a recording material and a fixing unit for fixing a toner image on the recording material to be transferred, a rotating shaft for rotating an image carrier has a disk-like shape. An image forming apparatus comprising: a flywheel that removes light from the inside. 6. The image forming apparatus according to claim 5, wherein the flywheel is provided with a movable member inside. 7. The image forming apparatus according to claim 6, wherein the flywheel fixes a movable member provided inside by a spring pin. 8. The image forming apparatus according to claim 6, wherein the flywheel has a movable member provided inside fixed by a spring.