Developing device and image forming apparatus using the same

Abstract

A developing device includes a developing vessel, first and second conveying passages for conveying a developer, first and second conveying members for agitating and conveying the developer, a developing roller, a toner supply port for receiving a supply of toner and an agitator arranged under the toner supply port. The first conveying member has a rotary shaft and first and second conveying blades formed on the periphery of the rotary shaft. The agitator is arranged coaxially with the first conveying member so as to be rotatable independently from the first conveying member. The agitator includes a circular helical blade formed around the outer periphery of the second helical blade.

Description

technical field [0001] The present invention relates to a developing device and an image forming apparatus using the developing device, in particular to a developing device using a two-component developer containing toner and a magnetic It is used in an image forming apparatus that forms an image with a toner, such as an xerographic copier, a laser printer, a facsimile, and the like; and an image forming apparatus that uses the developing device. Background technique [0002] Conventionally, image forming apparatuses based on electrophotography, such as copiers, printers, facsimile machines, etc., have been known. An image forming apparatus that uses electrophotography forms an electrostatic latent image on the surface of a photosensitive drum (toner image carrier), supplies toner to the photosensitive drum through a developing device to develop the electrostatic latent image, and forms the electrostatic latent image on the photosensitive drum through development. The toner...

AI Technical Summary

Problems solved by technology

[0011] When insufficiently charged toner is supplied, there is a tendency for the toner to scatter from the developing roller, staining the inside of the image forming apparatus and the formed image

In addition, if insufficiently charged toner is supplied to the developer, the electrostatic force for holding the toner on the surface of the carrier is low, so that there is also a problem that the toner tends to adhere to the non-image area and cause blurred images

[0013] However, even with the above-described developing device having a sieve member, a large amount of toner is added from the toner storage to the developer conveying passage, and the toner is conveyed to the top surface of the developer in a state of lumps (developer surface) and does not mix well with the carrier, thus causing problems in supplying undercharged toner to the developer roller

[0014] Also, a method of improving the mixing ability of the added toner and the developer by making the blade of the developer conveying member larger may be considered, but this causes a problem that excessive stress is applied to the developer, thus making the developer Breaks down quickly, shortening the life of the developer

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