Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
2000-06-02
2002-09-24
Pendegrass, Joan (Department: 2852)
Electrophotography
Image formation
Photoconductive member
C074S574300, C399S075000
Reexamination Certificate
active
06456807
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rotation stabilizing device deterring rotation fluctuation and thereby stabilizing the rotation, a rotation driving mechanism equipped with the rotation stabilizing device, and to an image forming apparatus and an image reading apparatus which can deter rotation fluctuation in an image carrier such as a photoreceptor drum.
In recent years, there are demands for the technology to stabilize driving in various technical fields. For example, in an image forming apparatus such as a copying machine, a developing agent, namely, toner is used for developing a latent image on a photoreceptor drum representing an image carrier. In general, toner is a powdery substance having a size of about 10 &mgr;m, and it is structured with resin and a magnetic substance, or with resin and an adhesive agent.
When forming an image, toner is adsorbed on a photoreceptor drum on which electric charges are accumulated, then, the toner is transferred onto paper representing an image forming object, and this toner is fixed on the paper by the use of a fixing roller. Toner which failed to be transferred and is remaining on a photoreceptor drum is removed from the photoreceptor drum by a scraping blade before succeeding electric charges are accumulated.
Incidentally, though torque transmitted through a driving system for rotating a photoreceptor drum is mostly constant, resistance of a scraping blade which comes in contact with an outer circumferential surface of the photoreceptor drum and scrapes toner off, for example, usually fluctuates irregularly. If this resistance increases, a rotating speed of the photoreceptor drum is low, while, if this resistance decreases, a rotating speed of the photoreceptor drum is high, thus, rotational fluctuation of the photoreceptor drum is intrinsically caused. When the rotational fluctuation is caused on the photoreceptor drum, an image is not formed uniformly, causing a fear of a decline of image quality.
For preventing rotational fluctuation of this kind, a fly wheel having the great moment of inertia is provided to be coaxial with the photoreceptor drum. Due to the great moment of inertia,: this fly wheel can absorb rotational fluctuation of the photoreceptor drum to a certain extent/
However, it was found that rotational fluctuation is still caused occasionally on the photoreceptor, even when a fly wheel having the great moment of inertia is provided. A fly wheel, a shaft connected to the photoreceptor drum and gears in a driving system form a torsional vibration system. In the torsional vibration system of this kind, there exists a natural frequency. Therefore, if resistance of a scraping blade which comes in contact with an outer circumferential surface of the photoreceptor drum, for example, generates vibratory force to start vibration at a frequency which is close to a natural frequency of the torsional vibration system, the so-called resonance phenomenon is caused on the torsional vibration system, and great torsional vibration is generated on the fly wheel. The torsional vibration of this kind causes rotational fluctuation of the photoreceptor drum and thereby affects adversely on image forming.
On the contrary, even if the moment of inertia of the fly wheel is further increased, the natural frequency still exists and it rather moves toward the low frequency side, and transmission magnification is increased, resulting in another trouble that resonance phenomenon tends to be caused.
Further, although the changing of torque from a driving system under an electronic control in accordance with fluctuation of resistance of a scraping blade can be considered, the control mechanism needs to be complicated and high-performance motors and expensive electronic parts are necessary, which increases cost of an image forming apparatus.
In addition, not only for the image forming apparatus, various technologies have been used as a stabilizing technology for driving of a body of rotation. For example, there is known a technology to arrange a damper for achieving stabilized driving of a motor. For example, Japanese TOKKAISHO No. 61-9156 discloses a damper for a stepping motor wherein a flange section and an inertia body both fixed on a motor shaft are combined together through an elastic member. However, since an elastic body is stuck to the flange section and an inertia body through adhesives or baking, it is not possible to change a position, the number and materials of the elastic body, and it is also impossible to change dimensions and materials of the flange sections and inertia bodies, resulting in less versatility and low degree of freedom in use. Further, even if the elastic bodies and inertia bodies are deteriorated, they can not be replaced, and a damper needs to be replaced totally. Since those with a conventional structure lack versatility as stated above, other types are necessary to be prepared in advance, which causes additional cost.
SUMMARY OF THE INVENTION
In view of the problems in the prior art, it is an object to provide a rotation stabilizing device which is versatile for use and has high degree of freedom and deters rotation fluctuation to stabilize the rotation, and a rotation driving mechanism, an image forming apparatus and an image reading apparatus all being equipped with the rotation stabilizing device.
Another object of the invention is to provide an image forming apparatus wherein the structure is simple, and rotational fluctuation of a body of rotation such as a photoreceptor drum can be deterred.
To attain the objects stated above, a rotation stabilizing device of the invention has therein a rotary member which rotates around the central rotation axis, an inertia member which is arranged at the position different from that for the rotary member in terms of the axial direction of the central rotation axis, and a connecting member which is provided with a viscoelastic member having viscosity and elasticity and connects the rotary member and the inertia member in a detachable manner through the viscoelastic member, and is characterized in that the connecting member is provided at the position which is away from the central rotation axis in the radial direction.
Owing to this rotation stabilizing device, fluctuation of rotating speed of the rotary member is controlled by vibration of the inertia member, and the viscoelastic member having viscosity and elasticity is deformed in accordance with vibration of the inertia member. Therefore, even in the case of generation of vibratory force that causes fluctuation of rotating speed on the rotary member, this fluctuation of rotating speed is controlled, and the rotary member can rotate stably. In addition, since the connecting member connects the rotary member and the inertia member in a detachable manner, it is easy to replace the viscoelastic member, the rotary member and the inertia member, combination of each member is more flexible, adjustment for stabilizing rotation is easier, thus, it is possible to realize a rotation stabilizing device having versatility in use and high degree of freedom. It is also possible to realize a rotation stabilizing device having construction which is of low cost and is strongly-built because of simple structure.
When there is provided a rotary shaft which is fixed on the rotary member and rotates solidly with the rotary member, this rotary shaft can be connected with a rotary shaft of a motor, and thereby, the rotation stabilizing device can be attached on the motor.
When the connecting member is equipped with an attaching member which attaches the viscoelastic member on the rotary member and on the inertia member, it is easy to attach the viscoelastic member.
When the attaching member is provided with a flange section which is formed solidly with the viscoelastic member, it is possible to attach the viscoelastic member on the rotary member and the inertia member. In this case, it is preferable to arrange so that the flange section of the attaching member may be interposed between the rotary member and the in
Fukuo Chohiko
Makino Toru
Onishi Jun
Saito Taku
Bierman, Muserlian and Lucas
Konica Corporation
Pendegrass Joan
LandOfFree
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