JP2000039752A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device that restricts the vibration of a drive transmission means to a minimum and obtains a high quality image stably. SOLUTION: A gear (drive transmission means) 22 being a separate part, which receives driving force from a motor (driving means) 5 first is supported at both ends so as to be freely rotatable, and also the gear 22 and the shaft (rotary shaft) 21 of the motor 5 are disposed on the same axis, and both are connected with a pin 24, thereby transmitting the driving force of the motor 5 to the gear 22. In the device, because the gear 22 disposed coaxially with the shaft 21 of the motor 5 and connected to the shaft 21 is supported at both ends, the vibration of the gear 22 is restricted to a minimum and the high quality image can stably be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art In recent years, the resolution of an image forming apparatus has been increased to 1200.
Higher image quality has been promoted, e.g., higher than the dpi class, and stripe-shaped density unevenness tends to appear on the image in the paper feeding direction due to uneven rotation of an image carrier such as a photosensitive drum. For this reason, uneven rotation countermeasures have become important, and in order to reduce the number of gears that transmit driving force from the gear shaft of the driving means such as a motor to the image carrier, and to minimize the influence of gear meshing errors. Means such as increasing the reduction ratio by using a relatively large-diameter gear have been adopted.

Further, in order to make it difficult for the fluctuation of the load other than the image carrier which causes the rotation unevenness to be transmitted to the image carrier, a motor for driving the image carrier is dedicated to driving the image carrier, or the motor itself has a large inertia. Since the motor has a moment, a motor is arranged between the image carrier and the other load so that the fluctuation of the load other than the image carrier can be absorbed by the inertia moment of the motor, or the motor and the image can be absorbed. Various measures have been taken to prevent the drive from being branched from the drive transmission system between the carriers to another load.

[0004]

However, in the above technique, as shown in FIG. 3, the number of gears 121a and 112 provided between the motor 105 and the drive shaft 111 of the image carrier such as a photosensitive drum is small. To the motor 105
Of the gear shaft 121, the accuracy of the gears 121a and 112, and the bearing 13 of the gear shaft 121 in the motor 105.
2a and 132b, eccentricity and rotational runout occur due to an error in attachment to the gears 112a and 132b.
In one rotation cycle of the motor 105. Side effects occur such that the influence of the fluctuation easily appears directly on the image as stripe-like density unevenness. In order to avoid such side effects, the vibration of the gear shaft 121 of the motor 105 and the gear 121a , 112 must be strictly controlled, which has caused a cost increase.

When the gear 121a is cut directly on the gear shaft 121 of the motor 105, the diameter of the shaft 121 is limited to a certain small value. Therefore, the number of teeth is secured by a small module to maintain the tooth shape of the gear 121a. Therefore, the module of the counterpart gear 112 has also been limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of stably obtaining a high-quality image by minimizing the vibration of a drive transmission unit. Is to do.

[0007]

In order to achieve the above object, according to the present invention, a drive transmission means, which is a separate component for first receiving a driving force from a driving means, is rotatably supported at both ends thereof. The drive transmission means and the rotation axis of the drive means are coaxially arranged, and the two are connected to transmit the driving force of the drive means to the drive transmission means.

According to a second aspect of the present invention, in the first aspect of the invention, at least one of the loads to which the driving force is transmitted via the drive transmitting means is an image carrier.

According to a third aspect of the present invention, in the second aspect, the drive transmission mechanism between the image carrier and the drive transmission means has no drive transmission path for branching to another load. It is characterized by.

Therefore, according to the present invention, since the drive transmission means which is disposed coaxially with the rotation axis of the drive means and is connected to the rotation shaft at both ends is supported, the vibration of the drive transmission means is minimized and the height is reduced. A quality image can be obtained stably.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an image forming apparatus according to the present invention. The image forming apparatus includes a sheet conveying device 1, a pair of sheet discharging rollers 2, 3, a control unit 4, a motor 5, and the like. In this image forming apparatus, a laser scanner 6 controlled by a controller draws a latent image on an image carrier 8 such as a photosensitive drum in a cartridge 7.

In the cartridge 7, the image carrier 8
The upper latent image is developed by toner to be visualized as a toner image, and the toner image is transferred onto the sheet at a transfer portion which is a contact portion between the sheet and the image carrier 8, and the sheet on which the toner image has been transferred is transferred. Is sent to the fixing unit 10 to receive the fixation of the toner image.

The drive shaft 1 for supporting the image carrier 8
1 has a large-diameter gear 12 attached thereto.
Meshes with a small-diameter gear 22 connected to a shaft 21 of the motor 5 (see FIG. 2).

Here, the details of the drive system of the image carrier 8 are shown in FIG.
A description will be given based on the cross-sectional view of FIG.

As shown in FIG. 2, the drive shaft 11 is rotatably supported by sheet metals 30a, 30b via bearings 31a, 31b, and a shaft 21 in the motor 5 is rotatable by bearings 32a, 32b. It is supported by.

In this embodiment, a gear 22 separate from the motor 5 is provided in place of the conventional gear shaft 121 shown in FIG.
The gear 22 is rotatably supported at both ends by a shaft 23 projecting from the gear b. Although one end of the gear 22 is supported by the shaft 23 here,
You may make it support with the same bearing as the bearing 25.

In the motor 5, both ends of the shaft 21 positioned coaxially with the gear 22 are provided with bearings 32.
The gear 22 is rotatably supported by a and 32b. The gear 22 is connected to an end of the shaft 21 by a pin 24. Here, the shaft 21 and the gear 22
Are connected by the pin 24, but the shaft 21 and the gear 22 may be connected by using a D-cut or various couplings.

By adopting the above configuration, the gear 22 corresponding to the conventional gear shaft 121 shown in FIG. 3 is supported at both ends by the bearing 25 and the shaft 23. And a high-quality image can be stably obtained without the appearance of stripe-like density unevenness on the image.

Although the diameter of the gear shaft 121 of the conventional motor 105 shown in FIG. 3 is limited to about 0.5 due to the limitation of the gear module of the gear shaft 121 and the gear 112, the present embodiment is not limited to this. According to this, a larger value can be selected as a module of the gears 12 and 22 depending on conditions such as a load.

Conventionally, as shown in FIG. 3, depending on the setting of the area of the gear 121a of the gear shaft 121, the presence of the imperfect gear portion causes the bearings 132a and 1
Although the distance between the shafts 32b is short, in this embodiment, no gear is formed on the shaft 21. Therefore, as shown in FIG. 2, the distance between the bearings 32a and 32b that support the shaft 21 is set to be longer than before. The shaft 21
Positioning accuracy can be improved.

Further, since the gear 22 according to the present embodiment can be obtained by molding as well as the conventional gear shaft 121 which is often manufactured by cutting a metal shaft, expensive cutting is minimized. Cost can be reduced.

[0023]

As is apparent from the above description, according to the present invention, the drive transmission means is disposed coaxially with the rotation axis of the drive means and supported at both ends by the drive transmission means. And a high-quality image can be stably obtained while minimizing the fluctuation of the image.

[Brief description of the drawings]

FIG. 1 is a sectional view of an image forming apparatus according to the present invention.

FIG. 2 is a partial cross-sectional view illustrating a configuration of a drive system of an image carrier of the image forming apparatus according to the present invention.

FIG. 3 is a partial cross-sectional view illustrating a configuration of a drive system of an image carrier of a conventional image forming apparatus.

[Explanation of symbols]

 Reference Signs List 5 motor (drive means) 8 image carrier (load) 21 shaft (rotating shaft) 22 gear (drive transmission means) 23 shaft 24 pin 25 bearing

Claims (3)

[Claims] 1. A drive transmitting means, which is a separate component that first receives a driving force from a driving means, is rotatably supported at both ends, and the drive transmitting means and the rotation axis of the driving means are coaxially arranged and connected to each other. An image forming apparatus configured to transmit the driving force of the driving unit to the driving transmission unit. 2. The image forming apparatus according to claim 1, wherein at least one of the loads to which the driving force is transmitted via the driving transmission unit is an image carrier. 3. The image forming apparatus according to claim 2, wherein the drive transmission mechanism between the image carrier and the drive transmission unit has no drive transmission path that branches to another load.