Developing device and image forming apparatus including same

A developing device comprising:

• a development casing configured to have an opening part and to accommodate developer containing toner;
• a developer carrying member supported by the development casing in a rotatable manner, the developer carrying member having a developing area in which a part of an outer circumference surface for carrying the developer is exposed through the opening part and faces an image carrying member, so that the toner is supplied to the image carrying member in the developing area;
• a regulating blade disposed on an upstream side of the developing area in a rotation direction of the developer carrying member, so as to regulate a layer thickness of the developer carried by the developer carrying member;
• a pair of pressing members configured to contact with both end parts of the developer carrying member in a rotation axis direction, so as to seal a gap between the development casing and the both end parts of the developer carrying member;
• and
• a blade seal member including a first layer material disposed inside the pair of pressing members in the rotation axis direction, so as to be laminated on an upstream side surface of the regulating blade in the rotation direction of the developer carrying member, and a second layer material laminated on a surface of the first layer material opposite to the regulating blade, the second layer material having a larger stiffness than the first layer material, wherein
• the development casing has a pair of facing surfaces that face each other in the rotation axis direction,
• the second layer material has positioning protrusions that protrude from the first layer material in the rotation axis direction at positions inside both ends of the first layer material in the rotation axis direction, so as to contact the pair of facing surfaces and be positioned in the rotation axis direction, and
• the first layer material is pressed in contact with the pressing member in the rotation axis direction, in a state where the second layer material is positioned in the rotation axis direction.