Patent ID: 7751744

Claim:
A development apparatus, comprising: a casing having an opening; a developer holder positioned in the opening of the casing and holding a powder developer in the casing on a surface of the developer holder to transport the powder developer; a regulation plate mounted on the casing in such a way that an end portion of the regulation plate comes close to the surface of the developer holder so as to regulate a layer thickness of the developer on the surface of the developer holder, the regulation plate extending in a direction orthogonal to a transportation direction of the developer on the surface of the developer holder; a smoky dust prevention sheet including a fixed end portion extending in the direction orthogonal to the transportation direction of the developer on the surface of the developer holder, wherein the fixed end portion of the smoky dust prevention sheet, is fixed onto a face of the regulation plate corresponding to a downstream side with respect to the transportation direction of the developer, and wherein the other end of the smoky dust prevention sheet, as a feed end portion, extends in the transportation direction of the developer, and is in contact with the surface of the developer holder, a curved inflection portion between the fixed end portion and the feed end portion defining a transition portion; a backup member having a main body portion for sandwiching the fixed end portion of the smoky dust prevention sheet with the regulation plate and extending in the direction orthogonal to the transportation direction of the developer on the surface of the developer holder and a reinforcement portion connected to the main body portion on a side of the developer holder, the reinforcement portion abutting the transition portion of the smoky dust prevention sheet.