Developing device with developing roller and thickness regulating member and image forming apparatus provided with same

A developing device, comprising:

• a housing configured to store developer containing toner and magnetic carrier;
• a developing roller including a fixed magnet having a plurality of magnetic poles along a circumferential direction and a sleeve configured to rotate in a predetermined rotating direction around the fixed magnet and carry the developer on a circumferential surface, the developing roller being so supported in the housing as to face a photoconductive drum, on a surface of which an electrostatic latent image is to be formed, at a predetermined developing position and supplying the toner to the photoconductive drum;
• a developer stirring member rotatably supported in the housing and configured to stir the developer and supply the developer to the developing roller;
• and
• a layer thickness regulating member arranged to face the sleeve of the developing roller and configured to regulate a layer thickness of the developer supplied to the developing roller by the developer stirring member;
• wherein:
• the fixed magnet has a regulation pole arranged to face the layer thickness regulating member and having a predetermined polarity;
• the layer thickness regulating member includes:
• a regulating body portion made of a magnetic material and configured to regulate the layer thickness of the developer being conveyed toward the developing position, the regulating body portion having a first facing surface arranged at a predetermined distance from the sleeve, a first upstream side surface connected to an upstream end part of the first facing surface in the rotating direction and extending along a radial direction of the sleeve and a first downstream side surface connected to the first facing surface on a side opposite to the first upstream side surface in the rotating direction;
• and
• an upstream regulating portion connected to the first upstream side surface of the regulating body portion, the upstream regulating portion having a second facing surface arranged to face the sleeve at a larger distance from the sleeve than the first facing surface, a second downstream side surface connected to a downstream end part of the second facing surface in the rotating direction, extending along the radial direction and held in close contact with the first upstream side surface and a second upstream side surface connected to the second facing surface on a side opposite to the second downstream side surface in the rotating direction;
• and
• the second facing surface of the upstream regulating portion has:
• a nonmagnetic facing surface made of a nonmagnetic material and arranged on a downstream end of the second facing surface in the rotating direction;
• and
• an upstream magnetic facing surface made of a magnetic material and arranged on an upstream end of the second facing surface which is upstream of the non-magnetic facing surface in the rotating direction.