Developing device, process cartridge, and image forming apparatus

A developing device for use in an image forming apparatus, the developing device comprising:

• a frame that accommodates a developer;
• a developer carrying member that is rotatably provided in an opening of the frame and carries and transports the developer;
• a supply member that supplies the developer to the developer carrying member, the supply member being in contact with the developer carrying member and being provided rotatably so as to move in the same direction with respect to the rotating developer carrying member at a contact portion thereof;
• and
• a regulating member that is blade-shaped, one end of the regulating member being fixed to the frame, and the other end of the regulating member, which is a free end extending in a direction opposite to a rotation direction of the developer carrying member, being in contact with the developer carrying member,
• wherein
• the regulating member comprising,
• an opposing portion that faces the developer carrying member, and
• a protrusion that protrudes toward the developer carrying member in the opposing portion facing the developer carrying member is provided;
• wherein the opposing portion comprising an opposing surface that faces the developer carrying member at a position further toward a tip side of the other end than the protrusion;
• and
• wherein a height of the protrusion from the opposing surface is denoted by H (mm) and a length of the opposing surface extending toward the tip side perpendicular to an axial line direction of the developer carrying member is denoted by L (mm), when viewing a cross section perpendicular to a rotation axis of the developer carrying member, the following conditions are satisfied:
• 0.05≦H≦0.1, and
• 0.15≦L≦1.0.