JPH112964A - Developing device - Google Patents

Abstract

(57) [Summary] [Problem] Regardless of the position of a developing device with respect to a photoconductor,
Provided is a developing device capable of reliably removing and collecting foreign matter such as a carrier attached to a photoconductor. A developing roller (2a, 3a) approaches a photosensitive member surface downstream of a photosensitive member (1) moving direction in conjunction with an approaching operation of the developing roller to the photosensitive member surface, and a photosensitive member of the developing roller. A first foreign matter collecting member (21, 31) that separates from the photoreceptor surface in conjunction with the separating operation from the surface, and separates from the photoreceptor surface in conjunction with the approaching operation of the developing roller to the photoreceptor surface; A second foreign matter collecting member (22, 32) is provided which approaches the photoconductor surface in conjunction with the operation of separating the roller from the photoconductor surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for an image forming apparatus typified by a laser printer, a copying machine, etc., and more particularly to a developing device using a powder developer containing toner particles and carrier particles. The present invention relates to a developing device that develops an electrostatic latent image.

[0002]

2. Description of the Related Art As a developing device used in an image forming apparatus, a developing device is provided so as to be able to approach / separate from the surface of a photoreceptor, and a powder developing device including a toner and a carrier around a developing roller provided in the developing device. There has been known a developing magnetic brush made of a developer, and an electrostatic latent image on the photoconductor is developed by the developing magnetic brush with the developing roller approaching the surface of the photoconductor. The configuration in which the developing device is retracted with respect to the surface of the photoconductor as described above is particularly capable of forming two or more colors or two or more types of images on the photoconductor by arranging a plurality of developing devices around the photoconductor. It is frequently used in the image forming apparatus described above. Then, only the developing device used for development is brought closer to the photoconductor, and the developing device not used for development is kept away from the photoconductor, and if the first development is completed, the developing device used for development is replaced. The next development is performed by separating the developing device that has not been used for the development from the photoconductor and approaching the photoconductor. By the way, in this type of developing device, even though a developing device not used for development is separated from the photoconductor, the carrier may scatter from the developing roller and adhere to the photoconductor. Therefore, conventionally, a configuration has been adopted in which a carrier collection roller is provided downstream of the developing roller in the direction of movement of the photoconductor to remove and collect the carrier attached to the photoconductor.

[0003]

However, only one carrier recovery roller in the prior art is provided downstream of the developing roller in the direction of movement of the photoconductor, and when the developing roller approaches the surface of the photoconductor. And the developing roller is separated from the surface of the photoreceptor when the developing roller is separated from the surface of the photoreceptor. Therefore, when the carrier collection roller is separated from the photoconductor, there is a disadvantage that the carrier attached to the photoconductor cannot be sufficiently collected. Here, if the carrier adhered on the photoreceptor cannot be collected, the adhered carrier hinders the close contact between the paper and the photoreceptor at the time of transfer, and the transfer in the peripheral area of the carrier is not sufficiently performed, so that a partial area on the image is not obtained. This leads to a problem that transfer is lost and a defective image is generated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to reliably remove and collect foreign matters such as carriers adhered to a photoreceptor regardless of the position of the development device relative to the photoreceptor. Is to provide.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to support a developing roller so as to be able to approach / separate from the surface of a photoreceptor and to form a developing magnetic brush made of a powder developer containing a toner and a carrier around the developing roller. A developing device for developing the electrostatic latent image formed on the photoconductor by the developing magnetic brush in a state where the developing roller is brought close to the surface of the photoconductor. The first foreign matter collection that approaches the photosensitive member surface in conjunction with the approaching operation of the developing roller to the photosensitive member surface and separates from the photosensitive member surface in conjunction with the separating operation of the developing roller from the photosensitive member surface A second foreign matter collecting member that separates from the photosensitive member surface in conjunction with the approaching operation of the developing roller to the photosensitive member surface and that approaches the photosensitive member surface in conjunction with the separating operation of the developing roller from the photosensitive member surface Department It is accomplished by having and.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the following description, an image forming apparatus that forms a two-color image will be described as an example.

In FIG. 1, reference numeral 1 denotes a photosensitive drum.
The photosensitive drum 1 starts rotating based on a recording operation start signal from a controller (not shown), rotates at a speed corresponding to the recording speed of the image forming apparatus, and continues to rotate until the recording operation ends.

When the photosensitive drum 1 starts rotating, a predetermined voltage is applied to a corona charger (not shown).
Charges the surface uniformly.

When character data and graphic data converted into a dot image are sent from the controller to the image forming apparatus as a laser beam on / off signal, the surface of the photosensitive drum 1 is irradiated with the laser beam from the portion not irradiated with the laser beam. An electrostatic latent image is formed. When the portion of the photosensitive drum 1 where the charge has disappeared due to the irradiation of the laser beam reaches a position facing the first developing device 2, a developing magnetic material formed of a powder developer containing toner and carrier formed around the developing roller 2a. The toner on the brush (not shown) is attracted by the static electricity to form a first toner image on the photosensitive drum 1.

When the first developing device 2 is used for development, the second developing device 3 is separated from the photosensitive drum 1.
Further, regarding a carrier collecting roller serving as a foreign matter collecting member,
In the first developing device 2, the carrier collecting roller 21 approaches the photosensitive drum 1, and in the second developing device 3, the carrier collecting roller 32 approaches the photosensitive drum 1 to remove and collect the carrier attached on the photosensitive drum 1. ing.

The photosensitive drum 1 holding the first toner image further rotates and enters a second rotation. The first developing device 2 and the second developing device 3 are provided at a predetermined timing during the second rotation image recording.
Is switched to the arrangement shown in FIG. In the second rotation, the developing roller 3a goes through the same process as in the first rotation.
The toner on a developing magnetic brush (not shown) made of a powder developer containing a toner and a carrier formed on the outer periphery is attracted by static electricity to form a second toner image on the photosensitive drum 1.

When the second developing device 3 is used for development, the first developing device 2 is separated from the photosensitive drum 1.
Further, regarding a carrier collecting roller serving as a foreign matter collecting member,
In the first developing device 2, the carrier collecting roller 22 approaches the photosensitive drum 1, and in the second developing device 3, the carrier collecting roller 31 approaches the photosensitive drum 1 to remove and collect the carrier adhered on the photosensitive drum 1. ing. In the drawings, reference numerals 23, 24, 33, and 34 denote scraping members that abut against a part of each carrier collection roller and scrape foreign substances such as carrier particles collected on the surface of the carrier collection roller.

When the first and second toner images are formed, a sheet (not shown) is conveyed in synchronization with the timing at which the first and second toner images on the photosensitive drum 1 reach the transfer position. The first and second toner images formed on the photosensitive drum 1 are sucked onto the sheet by the action of a transfer unit that applies a charge of a polarity opposite to that of the toner image to the back side of the sheet, and then fixed on the sheet by a fixing device. Is done. The area of the photosensitive drum 1 that has passed the transfer position is cleaned by the cleaning device, and is prepared for the next recording operation.

Although the above embodiment has been described based on the image forming apparatus in which the photosensitive drum is rotated by a number corresponding to the number of colors to be recorded, the first rotation of the photosensitive drum irradiates the laser beam. In the process, the first latent image area for the first toner image, the second latent image area for the second toner image, and the background area are collectively formed.
The same effect can be obtained even when applied to an image forming apparatus of a one-pass two-color configuration (a configuration in which two types of toner images are formed during one rotation of a photosensitive drum) employing a level exposure method. Also,
Laser beam irradiation sections are provided at two locations, a first irradiation section forms a first latent image area for a first toner image, and a second irradiation section forms a second latent image area for a second toner image. Even when applied to an image forming apparatus of a one-pass two-color configuration employing a method of forming an image area, the same effect can be obtained.

[0015]

As described above, according to the present invention, there is provided a developing device capable of reliably removing and collecting foreign matters such as carriers adhered to a photoreceptor regardless of the position of the developing device with respect to the photoreceptor. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a first state of a developing device of the present invention.

FIG. 2 is a schematic side view showing a second state of the developing device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (photoreceptor), 2 ... 1st developing device, 3 ... 2nd
Developing devices, 2a, 3a: developing rollers, 21, 22, 31, 3
2. Carrier recovery roller (foreign matter recovery member), 23, 24, 3
3, 34: scraping member.

Claims (1)

[Claims] A developing magnetic brush made of a powder developer containing a toner and a carrier is formed on an outer periphery of the developing roller so as to be able to approach / separate from the surface of the photoreceptor; In a developing device for developing an electrostatic latent image formed on the photoconductor with the developing magnetic brush in a state of being brought close to the body surface, a photoconductor of the developing roller is provided downstream of the developing roller in a photoconductor moving direction. A first foreign matter collection member that approaches the photosensitive member surface in conjunction with the approaching operation to the surface and separates from the photosensitive member surface in conjunction with the separating operation of the developing roller from the photosensitive member surface; and a photosensitive member of the developing roller. A second foreign matter collecting member that separates from the photoreceptor surface in conjunction with the approaching operation to the surface, and approaches the photoreceptor surface in conjunction with the separating operation of the developing roller from the photoreceptor surface. Image apparatus.