JP2007114434A - Developing unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing unit capable of attaining high image quality by dissipating and reducing vibration energy produced by a motor or the like and also by reducing vibration of a motor or the like which is a part that affects image formation, and to provide an image forming apparatus. <P>SOLUTION: The developing unit forms a visible toner image by supplying toner onto an electrostatic latent image on a photoreceptor drum subjected to scanning exposure with a laser beam in accordance with image information and thereby forming the electrostatic latent image. The developing unit has the developing motor for rotating the driving roller. An inertial field is attached, via an elastic body, to a side plate or a bracket attached to the side plate. The vibrations of the elastic body 3 and inertial field 4 reduce vibration energy produced by the motor. Thus, high image quality is achieved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing unit and an image forming apparatus, and more particularly, to a developing unit and an image forming apparatus in an electrophotographic laser printer, a copying machine, a facsimile, and the like.

  In recent years, documents processed in offices and the like have been rapidly colored, and image forming apparatuses such as copying machines, printers, and facsimiles that handle these documents have also been rapidly colored. Currently, these color devices tend to be improved in image quality and speeded up with the improvement and speed of office processing in offices and the like. As a color device that can meet such demands, for example, each color forming unit has black (K), yellow (Y), magenta (M), and cyan (C), and each image forming unit is formed. Various so-called tandem-type color image forming apparatuses that perform multiple transfer of images of different colors onto a transfer material or intermediate transfer member to be conveyed to form a color image have been proposed and have been commercialized. .

  One of the factors that hinders the improvement of the image quality of electrophotography is image deterioration caused by banded shading in an image called banding. One of the major factors governing this is vibration. Many vibrations in the image forming apparatus use a motor for driving each part as a vibration source. In particular, vibrations of the photosensitive member drive motor and the transfer belt drive motor that directly affect image formation cause the speed fluctuation vibration of the rotating body through the gears of the drive transmission system, and generate banding. Therefore, various countermeasures such as motor control and flywheel are taken as countermeasures for reducing these vibrations.

For example, in a color image forming apparatus having a driving device that is branched from a double-shaft dual-gear motor in a rotary driving device and that has an image carrier that is driven and transmitted by a gear train and an intermediate transfer member that is in pressure contact, A damper or flywheel is provided, and the amplification of vibration due to motor resonance is suppressed by the effect of the dynamic damper or flywheel provided on the motor shaft, thus suppressing the vibration of the image carrier. And a technique for preventing the occurrence of image disturbance in the latent image formed on the surface (see, for example, Patent Document 1).
JP-A-10-333385

  However, there is a drive portion of the developing unit as a drive system that does not take much consideration on vibration reduction despite having a vibration source that affects banding. The driving of the developing unit is a function for supplying toner by rotating the developing roller in order to create a toner image on the electrostatic latent image exposed on the photosensitive member. Therefore, many are not highly accurate with respect to speed fluctuations of the drive system. However, when the toner is supplied to the photosensitive member, the vibration of the developing roller propagates to the photosensitive member to cause a speed fluctuation and image degradation occurs. In view of the configuration, a developing driving motor is attached in the vicinity of the photosensitive member driving motor. In many cases, the vibration of the developing drive motor propagates to the photosensitive member drive system through the side plates and brackets, resulting in a fluctuation in the speed of the photosensitive member, which causes banding.

  In particular, when image quality is improved by the introduction of digital technology, the positional accuracy for each line of writing by laser is strictly required, and one of the factors governing this is the speed fluctuation of the rotary drive system. Reduction of speed fluctuations in a rotary drive system is an important technology for the development of products capable of obtaining high-quality images. The relationship between the visual sensitivity of images and the spatial frequency is said to be easily noticeable when the visual spatial frequency is in the range of about 0.3 to 2 lines / mm due to the characteristics of the human visual system. Considering this and the rotational speed of the photosensitive member, it is required to avoid vibration in a frequency range of several Hz to several hundred Hz.

  The present invention has been made in view of such a situation, and the cause is that the vibration of the developing drive motor propagates to the side plate and the bracket, and the vibration propagates to the photosensitive member drive motor attached to the bracket and the side plate. The image quality degradation is reduced by dynamic dampers to improve image quality, and the rotational vibration of the developing roller propagates when it contacts the photosensitive drum, and the rotational vibration is applied to the phenomenon that degrades the image. The purpose is to improve the image quality by reducing the dynamic damper.

  According to a first aspect of the present invention, there is provided a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotating the photosensitive drum, a developing roller, and a developing driving motor for rotating the developing roller. The developing unit is provided with an inertial body attached via an elastic body.

  According to a second aspect of the present invention, there is provided a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor that rotationally drives the photosensitive drum, a developing roller, and a developing driving motor that rotationally drives the developing roller. The developing unit is characterized in that an inertia body is attached to a bracket to which the development drive motor is attached via an elastic body.

  According to a third aspect of the present invention, there is provided a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. The developing unit is characterized in that an inertial body is attached to a side plate to which a bracket is attached via an elastic body.

  According to a fourth aspect of the present invention, there is provided a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotating the photosensitive drum, a developing roller, and a developing driving motor for rotating the developing roller. The developing unit is characterized in that an inertia member is attached to a shaft of a drive transmission system between the developing drive motor and the developing roller via an elastic member.

  According to a fifth aspect of the present invention, there is provided a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotating the photosensitive drum, a developing roller, and a developing driving motor for rotating the developing roller. The developing unit is characterized in that an inertial body is attached to the rotor of the development drive motor via an elastic body.

  According to a sixth aspect of the present invention, in the developing unit according to the fourth or fifth aspect, the inertial body attached via the elastic body is such that the elastic body and the inertial body are circular with respect to the rotation center of the shaft or the rotor. It is characterized by having no distribution in the circumferential direction.

  According to a seventh aspect of the present invention, in the developing unit according to any one of the first to sixth aspects, the natural frequency of the vibration system including the inertial body attached via the elastic body, and the development drive The rotational frequency of the motor is the same.

  According to an eighth aspect of the present invention, in the development unit according to any one of the first to seventh aspects, the natural frequency of a vibration system including an inertial body attached via the elastic body, and development drive The meshing frequency determined by the gear which is the drive transmission system of the motor matches.

  According to a ninth aspect of the present invention, in the developing unit according to any one of the first to eighth aspects, a plurality of inertial bodies attached via the elastic body are provided.

  The invention according to claim 10 includes at least one or more image carriers, optical writing means for performing optical writing on the surface of the image carrier according to image information to form a latent image, and the image carrier. An image comprising: developing means for developing the replacement image; transfer means for transferring the latent image on the image carrier onto a transfer body or intermediate transfer belt; and a fixing means for fixing the transferred image. A forming apparatus, comprising: a developing unit according to claim 1.

  The invention according to claim 11 includes at least one or more image carriers, optical writing means for performing optical writing on the surface of the image carrier according to image information to form a latent image, and the image carrier. A developing unit that develops the latent image on the image; a transfer unit that transfers the latent image on the image carrier onto a transfer member or an intermediate transfer belt; and a fixing unit that fixes the transferred image. An image forming apparatus comprising a plurality of developing units according to any one of claims 1 to 9.

  According to the present invention, when the vibration system formed by the elastic body and the inertial body vibrates, the vibration energy generated by the motor or the like is dissipated and reduced by the added vibration system, thereby affecting the image formation. The vibration of the motor that is the part to be given is also reduced, resulting in higher image quality.

  Hereinafter, a developing unit and an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and therefore technically preferable various kinds of limitations are given. However, the scope of the present invention is not limited to the following description. As long as there is no description which limits, it is not restricted to these aspects.

  FIG. 1 is a schematic configuration diagram showing a basic configuration of a tandem type image forming apparatus according to an embodiment of the present invention. A black image forming unit 200K that forms a black (K) image, a yellow image forming unit 200Y that forms a yellow (Y) image, and a magenta image forming unit that forms a magenta (M) image 200M and a cyan image forming unit 200C for forming a cyan (C) color image, and these four image forming units 200K, 200Y, 200M, and 200C are spaced apart from each other at a constant interval. It is arranged horizontally. The image forming units 200K, 200Y, and 200M are electrostatically attracted to the lower portion of the four image forming units 200K, 200Y, 200M, and 200C of black, yellow, magenta, and cyan. , A transfer belt 202 as an endless transfer material carrier for conveying the transfer paper 201 over the transfer position of 200C is disposed.

  The four image forming units 200K, 200Y, 200M, and 200C are all configured in the same manner. In the four image forming units 200K, 200Y, 200M, and 200C, as described above, four color toner images are sequentially provided. It is configured to form. The image forming units 200K, 200Y, 200M, and 200C for the respective colors are provided with a photoconductive drum 203. The surface of the photoconductive drum 203 is uniformly charged by a primary charging scorotron 204, and then image formation is performed. The laser beam 205 is scanned and exposed in accordance with image information to form an electrostatic latent image. The electrostatic latent image formed on the surface of the photosensitive drum 203 is developed with each color toner of black, yellow, magenta, and cyan by the developing device 206 of each image forming unit, and becomes a visible toner image. These visible toner images are subjected to pre-transfer charging by the pre-transfer charger 207 and then sequentially transferred onto the transfer paper 201 held on the transfer belt 202 by charging of the transfer charger 208. The transfer paper 201 onto which the toner images of the respective colors have been transferred is separated from the transfer belt 202, and then subjected to a fixing process by a fixing device (not shown) to form a color image. In the figure, 209 is a photoconductor cleaner, 210 is a photoconductor discharge lamp, 211 is a sheet peeling corotron, 212 is a transfer belt discharge corotron, 213 is a transfer belt cleaner, and 214 is a cleaning pretreatment corotron.

  2 and 3 are schematic configuration diagrams of the developing unit according to the embodiment of the present invention. As shown in the figure, the development unit is composed of a development drive motor 1, a bracket 2, an inertia body 3, an elastic body 4, a side plate 5, a photoreceptor drive motor 6, a gear 7, a photoreceptor drum 8, and a development roller 9. Yes. Development for forming a visible toner image by scanning and exposing a laser beam in accordance with image information and supplying toner onto the electrostatic latent image to the photosensitive drum 8 for forming the electrostatic latent image. The unit has a development drive motor 1 for rotationally driving the development roller 9. In the developing unit shown in FIG. 2, an inertial body is attached to a bracket to which a developing drive motor is attached via an elastic body. In the developing unit shown in FIG. 3, an inertial body is attached to a side plate via an elastic body.

  The side plate 5 or the bracket 2 attached to the side plate 5 has a configuration in which an inertial body is attached via an elastic body (added vibration system). The vibration generated by the motor propagates to the bracket 2 and the side plate 5, and the propagated vibration further propagates to the photoconductor drive motor 6 attached to the bracket 2 and the side plate 5, resulting in image degradation. The energy of such vibration is reduced by the vibration of the elastic body 3 and the inertial body 4 to improve the image quality. Further, the rotational vibration of the developing roller 9 is propagated when contacting the photosensitive drum 8 to deteriorate the image such as banding, thereby reducing the rotational vibration and improving the image quality. The elastic body in FIGS. 2 and 3 may or may not have a spring-like shape. If a rubber-based material having a high damping property is used, a vibration energy dissipation effect can be obtained. Further, the inertial body is not particularly limited, such as a metal or a resin.

  According to the above-described embodiment, vibrations of the bracket and the side plate are reduced, and shaking of a motor that is a part that affects image formation attached thereto is also reduced, so that high image quality can be achieved.

  FIG. 4 is a schematic configuration diagram showing that an inertial body is attached to a shaft of a drive transmission system between the development drive motor and the development roller according to the embodiment of the present invention via an elastic body. By adopting a configuration in which the elastic body 3c and the inertial body 4c are added to the shaft 11 in the drive transmission system of the developing roller, the elastic body and the inertial body vibrate and dissipate energy from the vibration component generated in the rotation direction. Rotational vibration that propagates to the developing roller is reduced, and image degradation is reduced. The elastic body 3c in FIG. 4 is preferably a rubber material having a high damping property, and the inertial body may be made of metal, resin, or the like, but is not limited thereto. In addition, it is preferable that the inertial body and the elastic body are uniformly distributed in the circumferential direction with respect to the rotation center of the shaft. This is because, when the distribution is not uniform, the inertia is biased with respect to the rotation direction, and the eccentric vibration that is particularly noticeable at twice the rotational vibration frequency accompanying the rotation is newly generated. In order to prevent eccentric vibration that may cause image deterioration, the distribution of the inertial body and the elastic body added to the rotating system needs to be uniform.

  According to the above-described embodiment, high image quality can be achieved, and a vibration component that is an integral multiple of the rotational vibration frequency caused by the added vibration system is not generated.

  FIG. 5 is a schematic configuration diagram showing that an inertial body is attached via an elastic body on the rotor of the development drive motor according to the embodiment of the present invention. By adopting a configuration in which the elastic body 4d and the inertial body 3d are added on the rotor 12 of the development drive motor, a rotational vibration component generated by the rotation of the development drive motor itself is formed by the elastic body 4d and the inertial body 3d. The vibration system vibrates to dissipate the vibration energy transmitted to the rotor 12, and the rotational vibration transmitted to the rotor 12 is reduced to reduce image degradation. Further, the inertial body 3d and the elastic body 4d are also distributed uniformly in the circumferential direction with respect to the rotation center of the motor shaft 13 and the rotor 12, thereby preventing the occurrence of eccentric vibration.

  According to the above-described embodiment, high image quality can be achieved, and a vibration component that is an integral multiple of the rotational vibration frequency caused by the added vibration system is not generated.

A drive system according to another embodiment of the present invention will be described. Main vibration components generated in the developing unit include the rotation frequency fm (Hz: hertz) of the developing drive motor 1 and the meshing vibration of the gear 7. The meshing vibration of the gear 7 is determined by fg = fm × z (Hz) from the rotational frequency fm of the developing drive motor 1 and the number of teeth z of the gear 7, and the gears 7 come into contact with each other when the gear 7 is meshed. Is a vibration source generated by. Therefore, in order to efficiently reduce the rotational frequency fm of the development drive motor 1 and the meshing vibration of the gear 7, the natural frequency of the vibration system formed by the inertia bodies 3 and the elastic bodies 4 is set as the development drive motor 1. Since the vibration component generated at fm (Hz) and fg (Hz) is dissipated by the vibration of the added inertial body 3 by matching the rotation frequency fm and the meshing frequency fg of the gear 7, the image quality is improved. Become. Here, the natural frequency of the vibration system composed of the inertial body 3 and the elastic body 4 is as follows. If the mass of the inertial body 3 is m and the rigidity of the elastic body 4 is k, the natural frequency fd of the vibration system is
fd = 1 / (2 ・ π) ・ √ (k / m)
It is possible to calculate by

  According to the above embodiment, the main vibration generated in the developing unit when the natural frequency of the vibration system composed of the inertial body 3 attached via the elastic body 4 matches the rotation frequency of the developing drive motor 1. The rotational vibration of the motor can be selectively reduced, and the rotational frequency vibration of the motor transmitted to the bracket 2, the side plate 5, and the developing roller 9 is reduced, and the image quality can be improved.

  Further, according to the above embodiment, the natural frequency of the vibration system composed of the inertial body 3 attached via the elastic body 4 and the meshing frequency determined by the gear 7 which is the drive transmission system of the development drive motor 1 are obtained. By matching, it becomes possible to selectively reduce the meshing frequency vibration, which is the main vibration generated in the developing unit, and the meshing frequency vibration propagated to the bracket 2, the side plate 5, and the developing roller 9 is reduced, High image quality can be achieved.

  FIG. 6 is a schematic configuration diagram of a developing unit according to the embodiment of the present invention. By constructing a vibration system composed of a plurality of elastic bodies 4 and inertia bodies 3 at various locations such as the side plate 5, bracket 2, and shaft 11 of the development unit, a plurality of vibration frequency components generated in the development unit can be reduced and high Image quality can be improved.

  According to the above-described embodiment, by having a plurality of inertial bodies 3 attached via the elastic body 4, vibration can be reduced for a plurality of vibration frequencies generated in the developing unit and affecting the image. Is possible.

  It can be considered that the developing unit according to the embodiment of the present invention is applied to an image forming apparatus or a color image forming apparatus.

  As mentioned above, the invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.

1 is a schematic configuration diagram showing a basic configuration of a tandem type image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a developing unit according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a developing unit according to an embodiment of the present invention. It is a schematic block diagram which shows that the inertia body is attached to the shaft of the drive transmission system which concerns on embodiment of this invention via the elastic body. It is a schematic block diagram which shows that the inertia body is attached via the elastic body on the rotor of the developing drive motor which concerns on embodiment of this invention. FIG. 2 is a schematic configuration diagram of a developing unit according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Development drive motor 2 Bracket 3 Inertial body 4 Elastic body 5 Side plate 6 Photoconductor drive motor 7 Gear 8, 203 Photosensitive drum 9 Developing roller 200K, 200Y, 200M, 200C Image forming unit 201 Transfer paper 202 Transfer belt 204 For primary charging Scorotron

Claims (11)

A developing unit comprising a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. ,
A developing unit, wherein an inertial body is attached via an elastic body. A developing unit comprising a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. ,
A developing unit, wherein an inertia member is attached to a bracket to which the developing drive motor is attached via an elastic member. A developing unit comprising a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. ,
A developing unit, wherein an inertial body is attached to a side plate to which a bracket is attached via an elastic body. A developing unit comprising a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. ,
A developing unit, wherein an inertia member is attached to a shaft of a drive transmission system between the developing drive motor and the developing roller via an elastic member. A developing unit comprising a photosensitive drum for forming an electrostatic latent image, a photosensitive drum driving motor for rotationally driving the photosensitive drum, a developing roller, and a developing driving motor for rotationally driving the developing roller. ,
A developing unit, wherein an inertia member is attached to a rotor of the developing drive motor via an elastic member.   6. The inertial body attached via the elastic body is characterized in that the elastic body and the inertial body do not have a distribution in a circumferential direction with respect to a rotation center of the shaft or the rotor. Development unit.   The natural frequency of a vibration system composed of an inertial body attached via the elastic body and the rotation frequency of the developing drive motor coincide with each other. Development unit.   2. The natural frequency of a vibration system composed of an inertial body attached via the elastic body and a meshing frequency determined by a gear which is a drive transmission system of a development drive motor coincide with each other. The developing unit according to any one of items 1 to 7.   The developing unit according to claim 1, comprising a plurality of inertial bodies attached via the elastic body. At least one image carrier;
Optical writing means for performing optical writing according to image information on the surface of the image carrier to form a latent image;
Developing means for developing a replacement image of the image carrier;
A transfer means for transferring the latent image on the image carrier onto a transfer body or an intermediate transfer belt;
An image forming apparatus comprising: a fixing unit that fixes the transferred image;
An image forming apparatus comprising the developing unit according to claim 1. At least one image carrier;
Optical writing means for performing optical writing according to image information on the surface of the image carrier to form a latent image;
Developing means for developing a latent image on the image carrier;
A transfer means for transferring the latent image on the image carrier onto a transfer body or an intermediate transfer belt;
An image forming apparatus comprising: a fixing unit that fixes the transferred image;
An image forming apparatus comprising a plurality of the developing units according to claim 1.

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