Developing apparatus with developer transporting screw

Abstract

Provided is a developing device, etc., having a screw shape which effectively prevents variations in screw pitch. The developing device supplies developer to a developing sleeve by rotating a screw and develops a latent image formed on a photoreceptor drum with developer. The screw has a spiral vane around a rotary shaft. The vane is formed so that an angle between the axis of the rotary shaft and a vane face is <=60[deg.].

Description

technical field [0001] The present invention relates to a developing device mounted on an image forming device of a copier, a printer, etc., in particular, to a developing device with a developer conveying screw. Background technique [0002] As a developing device mounted on an "image forming apparatus using an electrophotographic technique", a developing device using a two-component developer having very good chargeability to toner has been widely used. 7A and 7B show the configuration of a developing device using a general two-component developer, and FIG. 7A is a cross-sectional view and FIG. 7B is an explanatory plan view. [0003] 10 is a developer container containing a developer 11 formed of a toner and a carrier. A portion close to the opposite side of the photoreceptor drum 1 of the developer container 10 is provided with an opening portion provided with a developing sleeve 2 as a developer carrier. The developing sleeve 2 is a hollow non-magnetic metal sleeve, a...

AI Technical Summary

Problems solved by technology

[0011] The developer moves from the screw 5 to the surface of the developing sleeve 2, and then moves to the opposite part of the photoreceptor 1 with the rotation of the developing sleeve 2. Therefore, the uneven distribution of the developer brought by the above-mentioned screw 5 causes the surface of the developing sleeve 2 to As a result, the image in the longer direction of the photoreceptor 1 has uneven shading (hereinafter referred to as this kind of image defect as "uneven pitch of the screw")

[0012] In particular, such uneven pitch of the screw is very likely to occur when the arrangement of the developing sleeve 2 and the developer conveying screw 5 is designed to be close to each other for downsizing the device.

[0013] In order to avoid unevenness of the pitch of the screw in the image, even if the configuration relationship between the developing sleeve 2 and the screw, the magnetic pole relationship of the magnet in the developing sleeve, the regulation state of the thickness of the developer layer brought by the regulation member 4, etc. Each composition is optimized, but as long as the distribution of the developer conveyed by the screw is skewed due to the pitch of the screw blades, it is difficult to completely prevent

[0014] In addition, in a developing device using a two-component developer having toner and carrier, since the toner concentration of the developer changes according to the balance between toner consumption and replenishment, the amount of the developer increases or decreases during the operation of the device.

Especially when the amount of toner in the developing device is small, it is very difficult to completely prevent the occurrence of uneven pitch of the screw.

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