JPH0695558A - Rotor driving device - Google Patents

Abstract

PURPOSE:To enhance the quality of image by decreasing speed variation of the rotor of an electrophotography image output apparatus. CONSTITUTION:A rotary member 18, in which an oil, etc., having a high viscosity resistance, is contacted with a sensitive drum 2 in its position not related with image formation, and the damping coefficient ratio zeta of the drum 2 is raised so that a momentary speed variation can be damped quickly, and thereby the rotating speed is kept constant. Thereby the speed variation of the sensitive drum 2 as a rotor is decreased, and the quality of the image is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming output device such as a digital color copying machine or a digital color printer to which an electrophotographic process is applied.

[0002]

2. Description of the Related Art Demand for copying machines, printers and the like to which an electrophotographic process is applied has been increasing in recent years. As such image output devices, there are known ones using a cylindrical photosensitive drum inside and ones using a belt-shaped photosensitive drum, and in the case of using a photosensitive drum, a photosensitive drum is used. An image is formed by rotating the body drum about a central axis passing in the longitudinal direction, and in the case of a belt-shaped photoconductor, the photoconductor is attached to a drive roller and run. Specifically, electrostatic latent images are sequentially formed on the surfaces of these photoconductors, and if the electrostatic latent images are formed, toner of each color is attached to the formed electrostatic latent image, and the toner is developed and transferred to paper. To form an image on the paper surface. Hereinafter, the photoconductor drum and the drive roller for the belt-shaped photoconductor in the image output device will be referred to as a rotating body.

In such an image output device, in particular, in a digital image output device in which a laser beam is used to write an image on a photosensitive member, unless the rotating body is constantly rotating at a predetermined speed, it is high. I can't get good quality images. If the rotation speed of the rotating body changes, the intervals of the scanning lines due to the laser light will vary from place to place, resulting in uneven shading, and in the case of a color image, each color, generally yellow, magenta, Since cyan and black toners are layered on top of each other, the proportion of the toners of each color may be out of balance, and the color reproducibility may deteriorate.

[0004]

However, when an impact force is applied to the rotating body in an actual image output device, a member called a cleaning blade for wiping off the toner adhering to the surface of the photosensitive member is exposed to light. It may come into contact with the body surface, and the rotating body undergoes periodic fluctuations in rotation speed at that moment. In addition, the resulting speed fluctuation remains for a long time, and it takes a long time to settle, and during that time, the image is greatly disturbed.

[0005]

Therefore, in the present invention, in order to quickly converge the speed fluctuation due to such an impact force to maintain the speed constant and improve the image, the non-image portion of the rotating body, that is, the direct image A rotary member having a rotation resistance is brought into contact with a corner portion not related to image formation, a side surface of the rotation body, or the like so as to impart sliding resistance to the rotation body.

[0006]

By contacting the rotating member having the rotational resistance with the rotating member, the damping coefficient ratio is increased, and the settling time for impulsive load fluctuations such as crimping or releasing of the cleaning blade can be shortened, and vibration can be reduced. The convergence of can be accelerated. As a result, speed fluctuations of the rotating body when load fluctuations occur are reduced, and output image quality can be greatly improved. Further, the device can be downsized, the cost can be reduced, and the reliability of the entire system can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 11 shows an entire electrophotographic image output device using the rotating body of the present invention. The electrophotographic image output device 31 is internally provided with a photoconductor drum 2 as a rotating body, a developing unit 3, a drive mechanism for driving the photoconductor drum 2, and the like. FIG. 2 shows the photosensitive drum 2 and the drive mechanism 4.
The drive mechanism 4 includes a drive motor 5 and a gear group 6 connected to the drive motor 5.
The drive gear 11 of the photosensitive drum 2 is connected to the final gear 10 of the gear group 6.

FIG. 1 is a sectional view of the photosensitive drum 2. The photosensitive drum 2 is made of a cylindrical aluminum base material coated with an organic photosensitive material on its side surface, and has flanges 12 fixed to both ends. A drive shaft 13 is attached to the center of the flange 12, the drive shaft 13 is rotatably supported by a bearing 21, and the drive gear 11 described above is attached to the shaft end and meshes with the final gear 10. . Then, on the wall surface of the image output device 31 on the side of the flange 12, the rotating member 1
8 is attached.

The rotating member 18 is shown in FIG. Rotating member 18
Is composed of a support shaft 19 and a roller 20 rotatably attached to the support shaft 19, and highly viscous oil is applied between the support shaft 19 and the roller 20. The roller 20 is composed of an inner cylinder 23 made of metal and an outer cylinder 22 made of rubber covering the outer side thereof. This rotary member 18 is
A support shaft 19 is attached so that 0 is in contact with a corner of the photosensitive drum 2, that is, a portion that is not involved in image formation, and is parallel to the drive shaft 13 of the photosensitive drum 2. Therefore, when the photoconductor drum 2 rotates, the roller 20 having a viscous resistance rotates between the photoconductor drum 2 and the support shaft 19, and as a result,
The photosensitive drum 2 is adapted to rotate while receiving rotational resistance.

Here, in general, the transfer function G in vibration is
(S) is represented by the following formula.

[0012]

[Equation 1] In the equation, ζ is the damping coefficient ratio and ω _N is the natural frequency. From this equation 1, it can be seen that the transfer function G (s) becomes smaller when the damping coefficient ratio ζ is made smaller.

4 to 7 show the difference in damping state when the damping coefficient ratio ζ is changed. In each figure, the vertical axis represents amplitude and the horizontal axis represents time. 4 shows the case where the damping coefficient ratio ζ is 10%, FIG. 5 shows the case where the damping coefficient ratio ζ is 20%, FIG. 6 shows the case where the damping coefficient ratio ζ is 40%, and FIG. 7 shows the case where the damping coefficient ratio ζ is 60%. From this, it is understood that the damping coefficient ratio ξ is preferably in the range of 20% to 60%.

Thus, the support shaft 1 is attached to the photosensitive drum 2.
When the roller 20 having a viscous substance is brought into contact with the photosensitive drum 9 so as to rotate together, the damping coefficient ratio ζ of the photosensitive drum 2 increases, and for example, when the cleaning blade acts on the photosensitive drum 2. Even when an instantaneous speed fluctuation occurs, the speed fluctuation can be quickly attenuated to the original speed and the fluctuation of the rotation speed can be kept to a minimum. Therefore, the instantaneous speed fluctuation can be quickly attenuated, and the photosensitive drum 2 can be smoothly rotated at a constant speed.
The quality of the output image can be significantly improved.

FIG. 8 shows another embodiment of the rotating member 18. In this, a groove 24 is formed in the inner cylinder 23 in the circumferential direction, and highly viscous oil is sealed in the groove 24. With this configuration, the oil will not run out, a stable viscous resistance will always be obtained, the damping coefficient ratio ζ of the photoconductor drum 2 will be increased, and instantaneous speed fluctuations, such as when a cleaning blade comes into contact, will occur. It can be quickly damped to keep the rotation speed constant.

Furthermore, FIG. 9 shows another embodiment. this is,
Similar to the rotating member 18 shown in FIG. 8, there are grooves 24 in the inner cylinder 23, and baffle plates 27 are provided on the support shaft 19 at four places as shown in FIG. 10 so as to project toward the grooves 24. It is the one. By doing so, the roller 2 of the rotating member 18
Baffle plate 2 attached to support shaft 19 when 0 rotates
7 blocks the viscous oil that is trying to move together with the roller 20, so that a larger resistance can be obtained, and the damping coefficient ratio ζ of the photoconductor drum 2 is increased to momentarily when the cleaning blade comes into contact. It is possible to quickly attenuate various speed fluctuations and keep the rotation speed constant. The baffle plate 27 may be provided on the roller 20 side.

In the above example, the rotating body itself is the photosensitive drum 2.
However, the photosensitive drum 2 need not be a rotating body,
As shown in FIG. 12, a belt-shaped photosensitive member 25 may be provided, and the driving roller 26 for driving the photosensitive member 25 may be provided with the rotating member 18 of the present invention. Even in this case, by using each of the above-described embodiments as the drive roller 26, the drive roller 26 can be rotated without speed fluctuation, and therefore the photoconductor 25 can be transported at a constant speed, so that the output image quality is remarkably improved. Can be improved.

As described above, the attenuating coefficient ratio ζ of the photosensitive drum 2 or the driving roller 26 can be increased by bringing the rotating member 18 having a rotational resistance into contact with the non-image portion of the rotating body, and the cleaning blade. With respect to the instantaneous speed fluctuation due to the action of, etc., it can be settled in a short time, and thereby the image quality can be remarkably improved. Furthermore,
It can be realized by a compact mechanism, the device can be downsized, the cost can be reduced, and the reliability of the entire system can be significantly improved.

[0019]

According to the rotating body driving apparatus of the present invention, a roller having a highly viscous substance is brought into contact with the non-image forming portion of the rotating body to rotate the roller together with the rotating body. As a result, the damping coefficient ratio of the rotating body can be increased, and the rotating body can be constantly rotated at a predetermined speed regardless of the speed fluctuation due to the action of the cleaning blade or the like. As a result, step unevenness that occurs in the sub-scanning direction of the writing system, image unevenness called pitch unevenness is reduced,
A significant improvement in image quality can be obtained. Further, in the prior art, a device having a complicated and large-sized mechanism can be realized by a simple and compact mechanism, and the cost can be reduced by this. Furthermore, due to the simplified mechanism,
The reliability of the entire system can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a photosensitive drum according to the present invention.

FIG. 2 is a perspective view showing a photosensitive drum.

FIG. 3 is a sectional view showing a rotating member according to the present invention.

FIG. 4 is a graph showing a vibration damping state.

FIG. 5 is a graph showing a vibration damping state.

FIG. 6 is a graph showing a vibration damping state.

FIG. 7 is a graph showing a vibration damping state.

FIG. 8 is a sectional view showing another embodiment of the rotating member according to the present invention.

FIG. 9 is a sectional view showing another embodiment of the rotating member according to the present invention.

FIG. 10 is a sectional view showing another embodiment of the rotating member according to the present invention.

FIG. 11 is a sectional view showing an electrophotographic image output device according to the present invention.

FIG. 12 is a sectional view showing an electrophotographic image output device according to the present invention.

[Explanation of symbols]

 2 Photoconductor drum 11 Drive gear 12 Flange 13 Drive shaft 18 Rotating member 19 Support shaft 20 Roller 25 Photoconductor 26 Drive roller

Claims (3)

[Claims] 1. An image output apparatus having a drive system including a rotating body and a drive shaft for rotating the rotating body, and a motor and a drive transmission system for rotating the driving system. A rotating member composed of a support shaft and a roller mounted rotatably around the support shaft is abutted on the image portion in parallel with the shaft of the rotating body, and a viscous substance is placed between the shaft of the rotating member and the roller. A drive device for a rotating body characterized by being used. 2. The drive device for a rotating body according to claim 1, wherein a space is formed between the support shaft of the rotating member and the roller, and the viscous substance is enclosed in the space. 3. The drive device for a rotating body according to claim 2, wherein a baffle plate fixed to the support shaft or the roller is provided in the space of the rotating member enclosing the viscous substance.