Developing device having a resin replacement area, image forming apparatus, and method for manufacturing developing device

A developing device comprising:

• a developing container configured to store developer containing toner;
• a developing roller supported by the developing container in a rotatable manner about an axis extending in parallel to a first direction, so as to feed the toner to an image carrier by carrying the toner on its outer circumferential surface and rotating;
• a regulating blade attached to the developing container, the regulating blade having a plate-like shape whose longitudinal direction is the first direction, the regulating blade allowing an end part opposite to the side attached to the developing container to make a surface contact with the outer circumferential surface of the developing roller, so as to regulate thickness of the toner layer formed on the outer circumferential surface of the developing roller;
• a seal member made of elastic material so as to seal a gap between the developing container and the regulating blade;
• and
• a resin member formed by curing liquid resin, wherein
• the regulating blade includes a mounting plate attached to the developing container, and a blade plate made of a sheet material thinner than the mounting plate,
• the blade plate is joined to one surface of the mounting plate, and protrudes from the mounting plate in a second direction parallel to the one surface and perpendicular to the first direction, so as to make a surface contact with the outer circumferential surface of the developing roller,
• the developing container has a facing part that faces a step part of the regulating blade, which includes a step due to a thickness of the mounting plate, in a third direction perpendicular to the first direction and the second direction,
• the seal member has a resin placement area in which the resin member is disposed, at an end part in the first direction, and is squeezed and disposed between the regulating blade and the facing part in the third direction,
• the resin placement area is an area that penetrates the seal member in the third direction and is surrounded by a constituent material of the seal member from the first direction and the second direction,
• the resin placement area is disposed at a position overlapping the step part,
• the seal member includes
• a back seal member whose longitudinal direction is the first direction, and
• an end part seal member adjacent in the first direction to an end surface of the back seal member in the first direction,
• the back seal member has a recess that recesses from the end surface in the first direction inward in the first direction, and penetrates in the third direction, and
• the resin placement area is an area surrounded by an inner wall surface of the recess and the end surface of the end part seal member in the first direction.