Developing device and image forming apparatus

摘要

This disclosure relates to a developing device supplying a non-magnetic one-component developer onto an image bearing member on which an electrostatic latent image is formed. The developing device has an accommodating portion, a supply roller, a development roller, and a regulating member. The accommodating portion accommodates the developer. The supply roller holds the developer accommodated in the accommodating portion on the outer circumferential surface thereof. The development roller has a roller portion, and a rotational shaft member. The roller portion receives the developer supplied from the supply roller and holds a developer layer on the outer circumferential surface thereof. The rotational shaft member is arranged to extend along a rotational axis and has at least one magnet portion. The regulating member is a plate member arranged to be surface contacted onto the surface of the developer layer on the development roller and having part thereof configured of a magnetic member.

主权项

1. A developing device supplying a non-magnetic one-component developer onto an image bearing member on which an electrostatic latent image is formed, comprising:
an accommodating portion accommodating the developer; a supply roller holding the developer accommodated in the accommodating portion on the outer circumferential surface thereof; a development roller supplying the developer onto the image bearing member; the development roller having
a roller portion receiving the developer supplied from the supply roller and holding a developer layer on the outer circumferential surface thereof, anda rotational shaft member arranged to extend along a rotational axis and having at least one magnet portion; and a plate-shaped regulating member arranged to be surface contacted onto the surface of the developer layer on the development roller and having at least part thereof configured of a magnetic member, wherein a magnetic force (m1) of the at least one magnet portion is 60 [mT] or more, and wherein the magnetic force (m1) of the at least one magnet portion of the rotational shaft member, a saturation magnetization (m2) of the regulating member, and a distance (L) between the magnet portion and the regulating member are configured to satisfy a range of 90 to 200 of a biasing index which is calculated by a formula: (m1×m2)/L2.