JP2003255663A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a soiling of the inside of a machine due to scattering of magnetic toner. <P>SOLUTION: In a magnetic one component fixed developing device and a two component rotary developing device, a scattered toner collecting plate is provided along the rotation outer periphery of the two component developing device in the vicinity of a photoreceptor, which is fixed so that a two component developing sleeve is brought to the backside of the collecting plate and the scattered magnetic toner is collected to the collecting plate by using the magnetic force of a magnet. <P>COPYRIGHT: (C)2003,JPO

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 such as a copying machine or a printer.

[0002]

2. Description of the Related Art In a conventional electrophotographic image forming apparatus, especially an image forming apparatus for forming a chromatic image, a two-component developing method in which a non-magnetic toner and a magnetic carrier are mixed and used as a developer is known. Widely used. Two
The component development method has advantages over other currently proposed development methods such as image quality stability and device durability, but on the other hand, deterioration of the developer due to long-term durability, especially deterioration of the carrier Since it is unavoidable, it is necessary to replace the developer.

On the other hand, the one-component jumping development method using magnetic toner does not use a carrier, so that it is not necessary to control the toner concentration in the developer and there is no problem of carrier deterioration, so that the developer needs to be replaced. It is possible to obtain a stable image over a long period of time. On the other hand, there is a problem that it is difficult to use as a color toner because the magnetic substance is mixed.

Therefore, an image forming apparatus using a one-component jumping developing system for black and a two-component developing system for color has been proposed as having the advantages of the above two developing systems.

[0005]

However, the above-mentioned image forming apparatus has the following problems.
In general, in this type of configuration, a plurality of rotation switching type developing devices that accommodate a two-component developer on the downstream side in the rotation direction of the photoconductor are arranged with respect to a fixed type developing device that accommodates magnetic toner. Further, on the downstream side thereof, there are a post charger and a transfer roller, and a path through which the transfer material is conveyed is arranged in the vicinity of the post charger. In this configuration, the magnetic toner scattered from the fixed developing device on the upstream side adheres to the two-component developing device, the post charger, the transfer roller, and the transfer material,
In some cases, it could cause image defects.

In order to prevent this problem, there is a method of disposing a scattered toner collecting roller to which a voltage is applied and an air duct on the downstream side of the fixed developing device. In this case, however, the cost UP and the apparatus configuration increase. There was a problem. Also,
As a simple structure, there is a method of arranging the scattered toner collecting plate on the downstream side of the fixed developing device, but it has a drawback that it does not have a sufficient collecting ability because it does not work to attract the magnetic toner. . There is also a method of using a magnet for the collecting plate, but there is a problem that the magnetic force of the magnet of the developing sleeve in the vicinity is affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable and fair image quality stabilization in a color image forming apparatus using a one-component developing system and a two-component developing system.

[0008]

(Means) The above object is achieved by an image forming apparatus as described below.

The first aspect of the present invention is used in an image forming apparatus using an electrophotographic system and contains a two-component developer composed of a toner and a carrier for developing an electrostatic latent image on a photoconductor. An image forming apparatus having a plurality of rotation-switching two-component developing devices and a one-component developing device containing magnetic toner on the upstream side of the two-component developing device in the rotation direction of the photoconductor. A scattering magnetic toner collecting plate from the one-component developing device was arranged in the vicinity of the photoreceptor on the downstream side in the body rotation direction so as to be along the outer circumference of rotation of the two-component developing device, and the one-component developing device was used. During the image forming operation, one of the two-component developing devices is moved and fixed in the vicinity of the flying magnetic toner collecting plate to the side opposite to the one-component developing device to fix the flying toner from the one-component developing device. Is the two component By the magnetic force of the developer carrying body of the magnet of the apparatus, the said scattering magnetic toner collecting plates 1
An image forming apparatus characterized in that it is collected by attracting it to the component developing device side.

A second aspect of the present invention is an image forming apparatus characterized in that the scattered magnetic toner collecting plate is provided with a member for accumulating the collected scattered toner.

In a third aspect of the present invention, the scattered toner collected by the scattered magnetic toner collecting plate is rotated by utilizing the rotation of the two-component developing device and the magnetic force of a magnet in the two-component developing sleeve. An image forming apparatus, characterized in that it is moved on the scattered magnetic toner collecting plate.

(Operation) With the above structure, the magnetic toner scattered from the one-component developing device is attracted to the surface of the collecting plate by the magnetic force of the magnet of the two-component developing sleeve on the back side of the collecting plate. You can get the ability to collect.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An electrophotographic image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 is an overall schematic explanatory view of the electrophotographic image forming apparatus, and FIG. 2 is a schematic explanatory view of the constitution of the developing means.

In the electrophotographic image forming apparatus according to the present embodiment, as shown in FIG. 1, a photosensitive drum 1 which is an electrophotographic photosensitive member in which a photosensitive layer made of an organic photosensitive member is formed on a cylindrical substrate is provided. It is rotatably attached at a predetermined peripheral speed in the direction of arrow A in FIG. In this embodiment, the outer diameter is 5
A photosensitive layer made of an organic photosensitive material is formed in the shape of a 0 mm aluminum cylinder, and a surface protective layer for improving the releasability of the toner and preventing abrasion of the photosensitive layer is provided.

The peripheral surface of the photosensitive drum 1 is charged to a predetermined polarity and potential by a roller charger 2 which is a charging means. Then, the charged surface is modulated (turned on) in response to the pixel signal of the image information output from the exposure unit 3 and input from the image signal generating device such as an image reading device or a personal computer (not shown) via the print interface. By scanning exposure with the laser beam 4 that has been turned on / off), an electrostatic latent image of image information is formed. Reference numeral 5 denotes a laser light reflection mirror, which deflects the output laser light 4 from the exposure means 3 with respect to the photosensitive drum 1.

Reference numeral 6 denotes a developing means, which is a yellow developing device 6
The rotary developing means 6a includes Y, magenta developing device 6M, and cyan developing device 6C, and fixed developing means 6b having a black developing device 6B for black. The yellow developing device 6Y, the magenta developing device 6M, and the cyan developing device 6C each include a non-magnetic toner (-polarity) and a magnetic carrier.
The component developers are contained, and the mixing ratio is about 1: 9 in weight ratio, and the toner is replenished by the consumed amount from a replenishment path (not shown). Black developing device 6B
Contains a magnetic toner (-polarity).

The rotation developing means 6a is a rotation supporting device 6
1 is rotatably supported in the direction of arrow B in FIG. 1, and the above-described color developing devices 6Y, 6M, and 6C are sequentially opposed to the photoconductor drum 1 to perform development with toner of each color.

On the other hand, the fixed developing means 6b has a developing device for accommodating the black toner, which consumes a large amount, and is detachably attached to the main body of the apparatus. When the fixed developing means 6b is attached to the apparatus main body 7, as shown in FIG. 2, the developing sleeve 6b which is a rotatable toner carrier.
1 is the photosensitive drum 1 and a minute gap (50 μm in the present embodiment).
m-500 μm), and the developing sleeve 6b
A developing area for supplying the toner carried on the photosensitive drum 1 toward the photosensitive drum 1 is formed.

Further, the toner container 6b2 is provided with a feeding means 6b3 for feeding the toner to the developing sleeve 6b1 side, and a feeding roller 6b4 for feeding the toner fed by the feeding means 6b3 to the developing sleeve 6b1. Is housed. A rubber foam material such as polyurethane or silicone is preferably used for the supply roller 6b4 in order to achieve stable supply to the developing sleeve 6b1 and uniform toner application. Further, the supply roller 6
It is preferable that b4 is brought into contact with the developing sleeve 6b1 and is rotated in the direction of arrow C in FIG. 2 while providing a peripheral speed difference.

A developing blade 6b5 is provided above the developing sleeve 6b1 as a regulating member for regulating the layer thickness of the toner carried on the developing sleeve 6b1.
Further, below the developing sleeve 6b1, a blow-out prevention sheet 6b6 for preventing the toner from being blown out from the lower portion of the toner container 6b2 is provided.

In the construction of the developing means, the surface of the photosensitive drum 1 is charged by the roller charger 2. Next, the exposure scanning is performed by the exposure unit 3 whose ON / OFF is controlled according to the image data of the first color (for example, yellow), and the electrostatic latent image of the first color is formed on the photosensitive drum 1. The electrostatic latent image of the first color is developed and visualized by a yellow developing device 6Y containing a yellow agent of the first color. Then, the visible first toner image is
Intermediate pressure contact with the photosensitive drum 1 with a predetermined pressing force, rotationally driven in the direction of arrow D at a speed substantially equal to the peripheral speed of the photosensitive drum 1 (100 mm / s in this embodiment). At the nip portion with the transfer body drum 8, it is transferred onto the surface of the intermediate transfer body drum 8.

In this embodiment, the intermediate transfer drum is used.
8. From the NBR rubber etc. on the aluminum cylinder
The surface of the conductive elastic layer is made of carbon, fluororesin, etc.
Form a surface layer made of dispersed urethane resin with releasability
And the resistance value is about 10^Five-10^{1 0}Ω. cm, outer diameter 15
A 3 mm one is used.

At the time of transfer onto the intermediate transfer body drum 8, a preset voltage is applied to the drum 8 with a polarity opposite to the charging polarity (-) of the toner. At the time of this transfer, the toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer drum 8 is scraped off by the cleaning blade 9a, which is the cleaning means 9 pressed against the photosensitive drum 1, and is a waste toner container. Collected in 9b.

Then, the above transfer process is similarly repeated for other toners (magenta, cyan, black),
In each case, toner images of different color toners contained in the respective developing devices are sequentially transferred to the intermediate transfer drum 8 and stacked to form a color image.

Numeral 9 is a cleaning means for cleaning the surface of the photosensitive drum 1 after the toner image is transferred onto the intermediate transfer drum 8, and the cleaning blade 9a is connected to the photosensitive drum 1.
The toner remaining on the surface of the drum 1 is scraped off by being brought into contact with the surface.

Further, in FIG. 1, reference numeral 10 is a cleaner for removing the toner remaining from the intermediate transfer body drum 8 without being transferred to the transfer material P from the intermediate transfer body drum 8.

The transfer material P as a recording material is fed from the feeding cassette 11 to the intermediate transfer drum 8 one by one by a feeding roller 12a and a conveying roller 12b.
By applying a voltage having a polarity opposite to that of the toner from the back surface of the transfer material P to the transfer roller 13, a full color toner image on the side of the intermediate transfer body drum 8 is transferred and formed on the transfer material P.

Then, the transfer material P to which the full-color toner image has been transferred is separated from the intermediate transfer drum 8 and introduced into the fixing means 14, where the toner image is heat-fixed and discharged to the discharge tray 15. Is configured.

Next, with reference to FIG. 3, the features of the present embodiment, the positions of the two-component developing device and the flying magnetic toner collecting plate and the behavior of the flying magnetic toner during the developing operation in the fixed developing device 6b will be described. To do. The scattered toner collecting plate 20 includes the fixed developing device 6
At a position downstream of b in the drum rotation direction and close to the photosensitive drum 1, along the outer circumference of rotation of the rotary developing means 6a,
The photosensitive drum 1 and the two-component developing device are arranged so as not to come into contact with each other.

In this embodiment, the scattered toner collecting plate 2
No. 0 uses a non-magnetic SUS plate with a thickness of about 1.0 mm, but the material / shape is not limited to this, and it depends on the magnetic force of the magnet in the developing sleeve 6m1 and the distance to the fixed developing device. It is also possible to use a resin or a magnetic material as appropriate. 2 so that the position of the developing sleeve 6m1 is an optimum position for attracting the scattered magnetic toner to the collecting plate 20.
The component developing device 6m is fixedly arranged near the scattered magnetic toner collecting plate 20.

In the above structure, the magnetic toner scattered from the fixed developing device 6b is attracted to the collecting plate 20 side by the magnetic force of the magnet in the developing sleeve 6m1 and adheres to the surface of the collecting plate 20 to be collected. It Even if the developing device 6m subsequently rotates and moves away from the vicinity of the collecting plate, the collected scattered toner adheres to the collecting plate without leaving the collecting plate due to a mirror image force or other adhesion force. As described above, according to this embodiment, the scattered toner can be collected with a simple structure, and the image quality can be stabilized.

(Second Embodiment) In the configuration of the first embodiment, although the amount of scattered toner from the fixed developing device is very small, when the image forming operation is performed for a long time, the scattered toner is gradually scattered on the scattered toner collecting plate. Will accumulate. As a result, in the end, the scattered toner may not be retained on the collecting plate, and the scattered toner may spill off from the collecting plate and stain the lower two-component developing device, the intermediate transfer drum, the transfer material, and the like. It was

In this embodiment, in addition to the structure of the first embodiment, the collected scattered toner is provided with a storage member. Figure 4
As can be seen from the above, the scattered toner that cannot be held by the collecting plate 20 accumulates in the scattered toner accumulating member 20a located below. With this configuration, the scattered toner does not spill down from the collecting plate, and the above-mentioned problems do not occur.

(Third Embodiment) With the construction of the second embodiment, the above-mentioned problems do not occur in normal long-term durability,
For example, in a hot and humid environment, if the amount of scattered toner increases due to the low tribo of the magnetic toner, the capacity of the scattered toner storage member may be insufficient, and the scattered toner may eventually fall off. . Although there is a method of increasing the capacity of the scattered toner storage member, there is a limit because the space between the fixed developing device, the photosensitive drum and the rotating means is narrow.

In this embodiment, as shown in FIG. 5, the scattered toner collecting plate 20 is extended along the direction of rotation of the rotating means, and a second scattered toner accumulating member is provided in a space having a margin opposite to the photosensitive drum 1. 20b is provided, and the toner adhering to the collecting plate 20 is conveyed to and accumulated in the second accumulating member 20b by utilizing the rotation of the two-component developing device 6m by the rotating means 6a and the magnetic force of the magnet in the developing sleeve 6m1. I decided to do it.

With the above structure, the scattered magnetic toner does not spill from the collecting member 20a, and most of the scattered toner is accumulated in the second collecting member 20b, thus eliminating the above-mentioned problems. You can

[0037]

As described above, according to the present invention,
A plurality of rotation-switching two-component developing devices used in an electrophotographic image forming apparatus and containing a two-component developer composed of a toner and a carrier for developing an electrostatic latent image on a photoconductor. In an image forming apparatus having a device and a one-component developing device containing magnetic toner on the upstream side of the two-component developing device in the rotation direction of the photosensitive member, in the vicinity of the photoreceptor on the downstream side of the one-component developing device in the rotation direction of the photosensitive member. When the magnetic toner trapping plate from the one-component developing device is arranged along the vicinity of the outer circumference of rotation of the two-component developing device, and when performing the image forming operation using the one-component developing device, 2 above
One of the component developing devices is moved to the side of the flying magnetic toner collecting plate opposite to the one component developing device and fixed,
The scattered toner from the component developing device is collected by being attracted to the one-component developing device side of the scattered magnetic toner collecting plate by the magnetic force of the magnet in the developer carrying member of the two-component developing device. Image forming apparatus.
By doing so, it is possible to realize and provide image stabilization in a color image forming apparatus using the one-component developing method and the two-component developing method in a simple and fair manner.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a first embodiment of the present invention.

FIG. 4 is a diagram illustrating a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a third embodiment of the present invention.

[Simple explanation of symbols]

1. Photoconductor 2. Charger 6a. Rotary developer 6b. Fixed developer 8. Intermediate transfer body 9. Cleaning device 20. Scattered toner collector 20a. Scattered toner accumulation member 20b. Second scattered toner storage member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yusuke Ishida             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2H030 AA04 BB23 BB24 BB28 BB63                 2H077 BA10 CA11 CA15 EA03 EA13                       EA24 GA04 GA13

Claims (3)

[Claims] 1. A rotation switching system which is used in an image forming apparatus using an electrophotographic system and contains a two-component developer composed of a toner and a carrier for developing an electrostatic latent image on a photoconductor. An image forming apparatus having a plurality of two-component developing devices and a one-component developing device containing magnetic toner on the upstream side of the two-component developing device in the rotation direction of the photoconductor. In the vicinity of the photoconductor, a scattering magnetic toner collecting plate from the one-component developing device is arranged along the vicinity of the outer circumference of rotation of the two-component developing device, and an image forming operation using the one-component developing device is performed. During the operation, one of the two-component developing devices is moved and fixed in the vicinity of the flying magnetic toner collecting plate to the side opposite to the one-component developing device to fix the flying toner from the one-component developing device to the two-component developing device. Current status of component development equipment Agents by the magnetic force of the carrier body of the magnet, the image forming apparatus characterized by collecting by attracting the one-component developing device side of the scattering magnetic toner collecting plate. 2. The image forming apparatus according to claim 1, wherein the scattered magnetic toner collecting plate is provided with a member for accumulating the collected scattered toner. 3. The scattered magnetic toner is collected by the scattered magnetic toner collecting plate by utilizing the rotation of the two-component developing device and the magnetic force of a magnet in the two-component developing sleeve. The image forming apparatus according to claim 1, wherein the image forming apparatus is moved on a collecting plate.