JP2004264381A - Image forming apparatus and development device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents toner from scattering and floating from the ends of a development roller and forms a high quality image and to provide a development device used for the image forming apparatus. <P>SOLUTION: The image forming apparatus includes a rotary member 46K. The rotary member 46K is disposed upstream of a development position in the direction of the rotation of the development roller 43K. The rotary member 46K rotates in the opposite direction (in the direction of the arrow A) of the photoreceptor drum 41K and the development roller 43K. As a result, air eddies around the rotary member 46K. That is, a current of air flowing from the photoreceptor drum 41K to the development unit 43K is produced in the development position. The rotary member 46K itself is a helical screw. Therefore, it has an element that causes the thus produced current of air to flow from both right and left ends of the screw to the middle of it in the axial direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine and a printer, and a developing device used in the image forming apparatus. More specifically, the present invention relates to a developing device that stores toner and an image forming device that forms an image by supplying toner.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has a developing device for storing toner and a photosensitive drum for holding a toner image. In this image forming apparatus, an image is formed by the following image forming process. First, an electrostatic latent image is formed on the photosensitive drum. Then, as the formed electrostatic latent image approaches the developing device, the toner adhered to the developing roller of the developing device adheres to the electrostatic latent image. As a result, a toner image is formed on the surface of the photosensitive drum. Then, the toner image is transferred to a recording sheet or the like and fixed on the recording sheet or the like. Thus, an image is formed and output.
[0003]
In the image forming apparatus that forms an image with toner in this way, when toner is supplied from the developing device onto the photosensitive drum, a part of the toner becomes powder smoke from a gap between the developing device and the photosensitive drum. May float. Then, the floating toner (hereinafter referred to as “floating toner”) contaminates a charger and the like, which may adversely affect the image quality of an output image. As a technique focusing on the collection of the floating toner, there are Patent Documents 1 and 2, for example. The image forming apparatus described in Patent Document 1 includes a charging member to which a voltage having a polarity opposite to that of the floating toner is applied, and a wing rotating member positioned between the charging member and the charger. Then, an airflow is generated by the rotation of the wing-shaped rotating member, and the floating toner flows toward the vicinity of the charging member. The floating toner is collected on the charging member by collecting the floating toner. Further, in the image forming apparatus described in Patent Document 2, a toner seal roller is provided at a position close to the developing roller. Then, the roller is rotated in a direction opposite to the rotation direction of the developing roller, and an airflow for drawing the floating toner into the developing device is generated. Thus, the floating toner is collected.
[0004]
[Patent Document 1]
JP-A-8-194377 [Patent Document 2]
JP-A-2002-174951
[Problems to be solved by the invention]
However, the conventional technique described above has the following problems. That is, in the image forming apparatuses described in the respective patent documents, the floating toner floating in the gap between the developing device and the photosensitive drum can be collected. However, it is impossible to collect floating toner that has once leaked to the outside from the end of the developing roller. Therefore, the quality of the output image has not been maintained. Further, when the developing unit is replaced, the worker is stained by the floating toner.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional image forming apparatus. That is, an object of the present invention is to provide an image forming apparatus capable of forming a high-quality image by suppressing floating toner scattered from an end of a developing roller and a developing apparatus used in the image forming apparatus.
[0007]
[Means for Solving the Problems]
An image forming apparatus made to solve this problem is an image forming apparatus that forms an image with toner, and an image carrier that carries a toner image and a toner that is applied to the image carrier while rotating. And a rotating member having a component directed toward the center from both ends of the shaft and generating an airflow having a component directed toward the developing roller at a position where the developing roller applies toner on the image carrier. is there.
[0008]
In the image forming apparatus of the present invention, a rotating member that generates an airflow by rotating is disposed. The airflow has a component going from both ends of the shaft toward the center and a component going to the developing roller at a position where the developing roller applies the toner on the image carrier. Therefore, the floating toner at both ends of the developing roller is collected at the center of the rotating member. Thereby, the leakage of the floating toner to the outside can be suppressed, and the contamination of the charger and the like can be prevented. Therefore, a high quality image can be formed. In addition, the floating toner collected at the center is flowed toward the developing roller. As a result, the floating toner can be collected. In addition, it is less likely that the operator will be soiled when the developing unit is replaced.
[0009]
Further, the rotating member of the image forming apparatus of the present invention is located upstream of a position where the developing roller applies toner on the image carrier with respect to the moving direction of the developing roller, and performs counter rotation with respect to the developing roller. Then better. Alternatively, it is better that the developing roller is located downstream of the position where the toner is applied on the image carrier with respect to the moving direction of the developing roller, and rotates in the forward direction with respect to the developing roller. As a result, the floating toner can reliably flow toward the developing roller.
[0010]
Also, the developing device of the present invention is a developing device that contains toner and develops a toner image on an image carrier, and includes a developing roller that applies toner on the image carrier while rotating, and both ends of a shaft. And a rotating member for generating an airflow having a component directed to the developing roller at a position where the developing roller applies toner on the image carrier. The problem has also been solved in an image forming apparatus provided with the present developing device.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to an electrophotographic color copying machine.
[0012]
The image forming apparatus according to the present embodiment is a tandem type full-color copying machine having four image forming units arranged in parallel as shown in FIG. In detail, the color copying machine of the present embodiment includes an image reader 1 and a printer 2. Further, the printer unit 2 forms an image on the recording paper S based on the image data created by the image reader unit 1. Specifically, the printer unit 2 includes a control unit 3, image forming units 4K, 4C, 4M, and 4Y, a transfer belt 5, and a fixing device 8.
[0013]
The image forming units 4K, 4C, 4M, and 4Y include LED arrays 7K, 7C, 7M, and 7Y, image processing units 6K, 6C, 6M, and 6Y that form toner images, and transfer the formed toner images onto the transfer belt 5. , And primary transfer rollers 45K, 45C, 45M, and 45Y. Further, the image processing units 6K, 6C, 6M, and 6Y have photoconductor drums 41K, 41C, 41M, and 41Y that carry toner images, and the chargers 42K, 42C, 42M, and 42Y, and the developing roller 43K centered on the photoconductor drums 41K, 41C, 41M, and 41Y. , 43C, 43M, 43Y, rotating members 46K, 46C, 46M, 46Y, cleaners 44K, 44C, 44M, 44Y, and the like.
[0014]
Next, the K-color developing device will be described in detail. The same applies to other color developing units. The developing device contains a two-component developer containing a toner and a carrier. Further, the developing device has a developing roller 43K for carrying the developer. The developing roller 43K is disposed so as to face the photosensitive drum 41K. Development is performed at a position where the developing roller 43K and the photosensitive drum 41K face each other (hereinafter, this facing position is referred to as a “development position”). Note that the developing roller 43K and the photosensitive drum 41K are not in contact with each other. Therefore, there is a slight gap between the developing roller 43K and the photosensitive drum 41K. The developing roller 43K has a built-in fixed magnet roller, around which a cylindrical developing sleeve rotates counter to the photosensitive drum 41K.
[0015]
Next, the rotating member 46K will be described in detail. The rotating member 46K is arranged downstream of the developing position in the rotation direction of the photosensitive drum 41K as shown in FIG. Further, when viewed from the developing roller 43K, the developing roller 43K is disposed upstream of the developing position in the rotation direction of the developing roller 43K. The rotating member 46K performs counter rotation (around the arrow A in FIG. 2) with respect to the photosensitive drum 41K and the developing roller 43K. As a result, an eddy current is generated around the rotary member 46K. That is, near the developing position, an airflow is generated from the photosensitive drum 41K toward the developing roller 43K. The rotating member 46K itself is a screw on which a spiral paddle is formed as shown in FIG. This paddle is formed so as to be symmetrical about the center of the rotating member 46K. Therefore, the airflow generated by the rotation of the rotating member 46K around the arrow A in FIG. 2 is a helical airflow that also has components directed from both left and right ends to the center along the axial direction.
[0016]
Next, the operation of the developing roller 43K and the rotating member 46K will be described. The developing roller 43K is counter rotating with respect to the photosensitive drum 41K while holding the developing material. Then, at the developing position, toner is attached to the electrostatic latent image formed on the photosensitive layer of the photosensitive drum 41 </ b> K, thereby developing (developing) the image. At the time of development, toner having an insufficient charge amount is released from the developing roller 43K. Then, the released toner floats in a gap between the developing roller 43K and the photosensitive drum 41K. The floating toner is generated at any position in the axial direction of the developing roller 43K. That is, it occurs at both the center and the end in the axial direction.
[0017]
Here, the air current generated by the rotation of the rotating member 46K has a component that goes around the rotating member 46K and also goes from both ends of the rotating member 46K toward the center. Therefore, the floating toner generated at the axial end is collected at the axial center of the rotating member 46K. Further, the toner is flowed toward the developing roller 43K. Then, the toner is collected by the developing roller 43. Thereby, the floating toner is collected in the developing device.
[0018]
The rotation member 46K may be arranged upstream of the developing position in the rotation direction of the photosensitive drum 41K as shown in FIG. That is, the developing roller 43K may be disposed downstream of the developing position in the rotation direction of the developing roller 43K. In this case, the rotating member 46K rotates in the forward direction (around the arrow B in FIG. 4) with the photosensitive drum 41K and the developing roller 43K. Thus, an airflow from the photosensitive drum 41K to the developing roller 43K is generated at the developing position. Of course, the airflow also has a component that goes from both left and right ends to the center along the axial direction. That is, even in such an arrangement, floating toner can be collected as in the arrangement of FIG.
[0019]
Further, the rotating member 46K is not limited to a spiral screw. That is, any shape may be used as long as it generates an airflow from both ends of the rotating shaft toward the center along the axial direction. For example, as shown in FIG. 5, a screw having a half-moon shaped blade may be used. In the case of such a rotating member, half-moon-shaped paddles are alternately assembled so as to be symmetrical from the left and right ends in FIG. 5 to the center. Further, a roller having a spiral groove as shown in FIG. 6 may be used.
[0020]
Further, the rotating member 46K may be in a state of being divided at a central portion. That is, as shown in FIG. 7, it may have two rotating parts 461K and 462K. Further, the rotating components 461K and 462K may be helical screws or the like. Alternatively, a conical roller having a spiral groove as shown in FIG. 8 may be used. In the case of a rotating member having two rotating components, the number of rotations may be changed for each rotating component according to the amount of floating toner generated.
[0021]
Further, the rotating member 46K shown in FIG. 2 or FIG. 4 is disposed only on either the upstream side or the downstream side, but may be disposed on both sides. Further, the developing roller K is counter-rotated with respect to the photosensitive drum 41K, but may be rotated in the forward direction. In this case, the rotating member 46K may be disposed downstream of the developing position in the rotation direction of the photosensitive drum 41K. This is because the floating toner tends to move downstream from the developing position in the rotation direction of the photosensitive drum 41K due to the airflow generated by the rotation of the photosensitive drum 41K and the developing roller 43K. The rotating member 46K rotates counterclockwise with respect to the photosensitive drum 41K and rotates in the forward direction with respect to the developing roller 43K. As a result, an airflow toward the developing roller 43K is generated at the developing position, and the floating toner is collected by the developing roller 43K. Note that the rotating member 46K may be disposed upstream of the developing position in the rotation direction of the photosensitive drum 41K. In this case, the rotating member 46K rotates counterclockwise with respect to the developing roller 46K and rotates in the forward direction with respect to the photosensitive drum 46K.
[0022]
Further, it is more preferable that a cap covering the non-magnetized portion is attached to the non-magnetized portion at the end of the developing roller 43K. As a result, the closing property of the end of the developing roller 43K is improved, and the amount of floating toner generated itself can be reduced.
[0023]
As described in detail above, in the image forming apparatus of the present embodiment, the rotating members 46K, 46C, 46M, 46Y are arranged near the developing position. A symmetrical spiral paddle is formed on each rotating member from both ends in the axial direction toward the center. Therefore, when each rotating member rotates, an airflow is generated from each photosensitive drum to each developing roller near the developing position and from each end of each rotating member to the center. Floating toner generated at both ends of each developing device by the airflow is collected at the center of each rotating member. Further, the toner is flowed toward each developing roller and collected in each developing device. Thereby, contamination of the charger by the floating toner can be suppressed. In addition, it is less likely that the operator will be soiled when the developing unit is replaced. Accordingly, an image forming apparatus capable of forming a high-quality image by suppressing floating toner scattered from the end of the developing roller and a developing apparatus used for the image forming apparatus have been realized.
[0024]
Note that the present embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, in the image forming apparatus of the present embodiment, a photosensitive drum is used as an image carrier, but the invention is not limited to this. For example, it may be a photosensitive belt.
[0025]
In the embodiment, the present invention is applied to a copying machine, but the present invention is not limited to this. That is, a printer, a facsimile or the like can be applied as long as it has a developing device. Further, the image may be dedicated to a monochrome image. Further, the present invention is not limited to the tandem system, and may be, for example, a four-cycle system.
[0026]
【The invention's effect】
As is apparent from the above description, according to the present invention, there is provided an image forming apparatus capable of suppressing floating toner scattered from the end of the developing roller and forming a high quality image, and a developing apparatus used in the image forming apparatus. Are provided.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating an overall configuration of an image forming apparatus according to an embodiment.
FIG. 2 is a schematic diagram (part 1) illustrating an arrangement of a rotating member in an image forming unit.
FIG. 3 is a schematic view showing a shape of a rotating member.
FIG. 4 is a schematic diagram (part 2) illustrating an arrangement of rotating members in an image forming unit.
FIG. 5 is a diagram (part 1) illustrating a modification of the shape of the rotating member.
FIG. 6 is a diagram (part 2) illustrating a modification of the shape of the rotating member.
FIG. 7 is a diagram (part 3) illustrating a modification of the shape of the rotating member.
FIG. 8 is a diagram (part 4) illustrating a modification of the shape of the rotating member.
[Explanation of symbols]
41K photoreceptor drum (image carrier)
43K developing roller 46K rotating member

Claims (4)

In an image forming apparatus that forms an image with toner,
An image carrier for carrying a toner image;
A developing roller for applying toner on the image carrier while rotating;
A rotating member having a component flowing from both ends of the shaft toward the center and generating an airflow having a component flowing toward the developing roller at a position where the developing roller applies toner on the image carrier. Image forming apparatus. The image forming apparatus according to claim 1,
The image is characterized in that the rotating member is located upstream of a position where the developing roller applies toner on the image carrier with respect to a moving direction of the developing roller, and rotates counter with respect to the developing roller. Forming equipment. The image forming apparatus according to claim 1,
The rotating member is located downstream of a position where the developing roller applies toner on the image carrier with respect to a moving direction of the developing roller, and rotates in a forward direction with respect to the developing roller. Image forming apparatus. In a developing device that contains toner and develops a toner image on an image carrier,
A developing roller for applying toner on the image carrier while rotating;
A rotating member having a component flowing from both ends of the shaft toward the center and generating an airflow having a component flowing toward the developing roller at a position where the developing roller applies toner on the image carrier. Developing device.

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