JP2002251102A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device capable of preventing a photoreceptor from causing irregular rotation without using a flywheel by absorbing the irregular rotation of a driving motor. SOLUTION: This image forming device is provided with a photoreceptor drum 1 for forming an image, a drum supporting shaft 2 supporting the drum 1 and the driving motor 4 driving the shaft 2. In the device, the shaft 2 is coupled with the drum 1 through an elastic body 3, whereby the drum 1 is supported by the shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a rotational driving force of a drive motor is transmitted to a photosensitive member to rotate the photosensitive member so that an electrostatic latent image is formed on the surface of the photosensitive member. Related to the device.

[0002]

2. Description of the Related Art Conventional image forming apparatuses such as copiers and printers to which electrophotography and the like are applied employ an image forming process after forming an electrostatic latent image on the surface of a photoconductor such as a photosensitive drum or a photosensitive belt. Then, the electrostatic latent image formed on the surface of the photoreceptor is developed with a developer, toner is adhered to the toner image as a visible image, and the toner image is transferred and fixed on a copy body such as paper. To form high-quality images.

In this image forming process, usually, the rotational force of a drive motor is transmitted to a photosensitive member such as a photosensitive drum or a photosensitive belt via a gear power transmission mechanism (drive transmission mechanism) such as a gear. While rotating, the surface (photosensitive surface) of the photoreceptor, which is the surface to be scanned, is optically scanned with a laser beam or the like to form an electrostatic latent image on the surface of the photoreceptor.

In such a toner-type image forming apparatus, a high-quality image can usually be obtained in the image forming process. However, when scanning the surface to be scanned with a light beam, the distance between sub-scanning lines is limited. Unevenness may occur.

[0005] This is caused by fluctuations in the rotation speed of the drive motor itself, vibrations caused by eccentricity of the shaft, fluctuations in the speed of the transmission system generated at the meshing portion of the gears, fluctuations in the natural vibrations caused by resonance, and the like.

If the rotation speed of the surface to be scanned fluctuates due to such a cause, the writing line interval in the sub-scanning direction becomes inconsistent, so that image pitch unevenness or image density shading phenomenon called jitter occurs. In this case, the image quality is significantly reduced.

[0007] This phenomenon is caused by the recent increase in image writing density and the 5.0-9.
The use of a toner having a small particle diameter of 0 μm has made a great close-up as the demand for higher image quality in the market has increased, and has become a major problem as the reproduction accuracy of development has improved. .

Therefore, it is important to form an electrostatic latent image by means of high-precision optical scanning for writing an image and high-precision position control of the surface to be scanned.

[0009]

With respect to the position control of the surface to be scanned, conventionally, a large and heavy flywheel is generally installed on a rotating body to keep the rotation constant.

Incidentally, in recent years, the above-mentioned image forming apparatuses tend to be small in weight and small in size. However, when a large and heavy flywheel is used as described above, the overall weight of the image forming apparatus increases,
There is a problem that the entire apparatus becomes large.

On the other hand, for example, Japanese Patent Laid-Open No. 59-15 / 1984
As described in Japanese Patent Application Laid-Open No. 221-221 and Japanese Patent Application Laid-Open No. H5-40398, the scanning line is detected by detecting the speed of the surface to be scanned and changing the optical scanning position of the light beam when the speed fluctuates. There has been proposed an improvement in an optical scanning device that corrects uneven scanning line spacing (pitch unevenness) in the sub-scanning direction when optically scanning a scanned surface with a light beam so as to prevent uneven spacing.

In such an apparatus, a sensor for detecting a speed fluctuation and an advanced control of a light beam accompanying the speed fluctuation are required, and the cost of the apparatus tends to increase.

Therefore, the present invention eliminates the drawbacks of the conventional drive transmission mechanism, absorbs the rotation unevenness of the drive motor, and prevents the photosensitive member from generating rotation unevenness without using a flywheel. It is to provide a device.

[0014]

In order to achieve the above object, according to the present invention, there is provided a photosensitive member for forming an image,
In an image forming apparatus having a drum support shaft that supports the photosensitive member and a drive motor that drives the drum support shaft, the photosensitive member is connected to the drum by elastically connecting the drum support shaft and the photosensitive member. The image forming apparatus is supported on a support shaft.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the elastic body is made of a polymer material.

Further, the image forming apparatus according to the third aspect is characterized in that, in the image forming apparatus according to the first aspect, the elastic body is made of raw rubber.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the elastic body is made of synthetic rubber.

[0018]

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

FIG. 1 is a schematic explanatory view of a photosensitive member rotation drive mechanism of an electrophotographic image forming apparatus.

In FIG. 1, 1 is a cylindrical photosensitive drum (photoreceptor), 2 is a drum support shaft disposed at the center of the photosensitive drum 1, and 3 is fixed to the drum support shaft 2 and the inner surface of the photosensitive drum 1. Elastic body. The elastic body 3 is formed of an elastic member such as a polymer substance or raw rubber or synthetic rubber. The elastic body 3 is fixed to the drum support shaft 2 and the inner surface of the photosensitive drum 1 by, for example, baking or bonding.

Reference numeral 4 denotes a drive motor for driving the photosensitive drum, and reference numeral 5 denotes a power transmission mechanism for transmitting the rotation of the drive motor 4 to the photosensitive drum 1.

The power transmission mechanism 5 includes a gear transmission 4a interlocked with an output shaft (not shown) of the drive motor 4, and a drive gear 6 attached to the output shaft 4b of the gear transmission 4a.
A gear 7 meshing with the drive gear 6 and a timing gear (timing belt pulley) 8 integral with and coaxial with the gear 7
A timing gear (timing belt pulley) 9 as a driven gear attached to the drum support shaft 2, and a timing belt 10
Having.

Next, the operation of the photoreceptor rotation drive mechanism having such a configuration will be described.

In such a configuration, when the drive motor 4 is operated by a copy switch (not shown) or a print command from a personal computer, the rotation of the drive motor 4 causes the gear transmission 4a, the output shaft 4b, and the drive gear 6 to rotate. Is transmitted to the drum support shaft 2 via the gear 7, the timing gear 8, the timing belt 10, and the timing gear 9. As a result, the drum support shaft 2 is driven to rotate, and the photosensitive drum 1 is rotated.
Rotate integrally with the drum support shaft 2 via the elastic body 3.

With the rotation driving of the photosensitive drum 1,
Laser beam scanning optical system (image forming optical system) not shown
As a result, a laser beam for forming an image is scanned on the surface (photosensitive surface) of the photosensitive drum 1 which is the surface to be scanned, and an electrostatic latent image is formed on the surface of the photosensitive drum 1. Such an image forming process is performed by a known configuration and method.

In such an image forming process, the power supply voltage of the image processing apparatus may fluctuate, and the rotation speed of the drive motor 4 itself may fluctuate. Further, in the power transmission mechanism (power transmission system) 5, it is conceivable that a speed variation is likely to occur at a meshing portion between the gears 6 and 7 and a meshing portion between the timing gears 8 and 9 and the timing belt 10. Furthermore, a power transmission mechanism (power transmission system)
In 5, when the output shaft 4b and the shafts of the gears 7, 8, and 9 are eccentric, vibration is generated. In addition, with this vibration, each member of the power transmission mechanism 5 and the photosensitive drum 1
It is also conceivable that a member that supports the above, or a bracket or a frame (not shown) that supports them resonates, and a speed fluctuation is likely to occur in the power transmission mechanism (power transmission system) 5 due to natural vibration due to the resonance.

However, in this embodiment, an elastic material having an optimum material and volume is selected as the material of the elastic body 3 in consideration of the rotational speed and inertia of the photosensitive drum 1 in particular, and the elastic body 3 has a certain size. By having a mass, the elastic body 3 can have a function of a flywheel. That is, by using an elastic material of an appropriate material as described above, for example, an elastic material such as a polymer substance or raw rubber or synthetic rubber as the material of the elastic body 3, and selecting the volume and thickness of the elastic body 3, etc. In addition, the elastic body 3 can have a relatively large mass. By doing so, even if the rotational speed of the surface (scanned surface) of the photosensitive drum 1 fluctuates as described above, the elastic body 3 has a large mass to some extent so that the elastic body 3 can fly. Since the rotation speed of the surface of the photosensitive drum 1 is prevented from fluctuating by exhibiting the same function as the wheel, the photosensitive drum 1 can be rotated at a constant speed without using a flywheel.

As described above, by using an elastic material of an appropriate material as the material of the elastic body 3, for example, an elastic material such as a polymer substance or raw rubber or synthetic rubber, a wide range of vibrations generated by the power transmission mechanism 5 can be obtained. Elastic body 3 for frequency component
The vibration can be prevented from being transmitted to the cheering drum 1 beforehand, and the speed fluctuation of the photosensitive drum 1 can be suppressed.

Therefore, the laser beam is scanned by a laser beam scanning optical system (image forming optical system) (not shown),
When an electrostatic latent image is formed on the surface of the photosensitive drum 1, the writing line interval in the sub-scanning direction of the laser beam by the laser beam scanning optical system (image forming optical system) becomes constant, and an image called image pitch unevenness or jitter is generated. The occurrence of the density shading phenomenon is prevented beforehand, and the image quality is prevented from deteriorating.

Therefore, as described above, not only the rotational speed of the photosensitive drum 1 is kept constant, but also the flywheel is not used, so that the entire apparatus can be reduced in weight, size and cost.

[0031]

As described above, according to the first aspect of the present invention, there is provided an image forming apparatus having a photosensitive member for forming an image, a drum supporting shaft for supporting the photosensitive member, and a driving motor for driving the drum supporting shaft. In the forming apparatus, the drum support shaft and the photoreceptor are connected by an elastic body so that the photoreceptor is supported on the drum support shaft. It is possible to prevent the rotation of the photoreceptor from occurring without using the photoreceptor. In addition, even if vibration occurs in the power transmission system from the drive motor, the vibration is prevented from being absorbed by the elastic body and transmitted to the photosensitive member. Furthermore, since no flywheel is used, the weight of the entire apparatus, compactness, and cost can be reduced.

Further, when the elastic body is made of a polymer material, when the elastic body is made of raw rubber, or when the elastic body is made of synthetic rubber, the drum support shaft and the photosensitive body are separated. Simple and easy to connect with elastic body

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a power transmission mechanism of an image forming apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (photosensitive body) 2 ... Drum support shaft 3 ... Elastic body 4 ... Drive motor

Claims (4)

[Claims] 1. An image forming apparatus comprising: a photosensitive member for forming an image; a drum supporting shaft for supporting the photosensitive member; and a drive motor for driving the drum supporting shaft. An image forming apparatus, wherein the photosensitive member is supported on the drum support shaft by coupling with an elastic body. 2. The image forming apparatus according to claim 1, wherein said elastic body is a polymer. 3. The image forming apparatus according to claim 1, wherein said elastic body is made of raw rubber. 4. An image forming apparatus according to claim 1, wherein said elastic body is made of synthetic rubber.