Cassette with winding slack preventing mechanism

摘要

Reels for carrying a sheet-like medium wound thereon are provided in parallel relation in a cassette case in a manner rotatable and shiftable longitudinally of the reels. A reel-biasing leaf-spring assembly is provided adjacent to one longitudinal end of each reel to bias the reel in a longitudinal direction. The leaf-spring assembly has a leaf-spring portion exerting the biasing force to the reel via an end projection on the reel, and rotation preventing arm angularly extending from the leaf-spring portion to normally engage a rotation preventing stub shaft carrying said projection thereon, the stub shaft having thereabout a plurality of flat outer surfaces one of which is engaged by said rotation preventing arm, whereby the reel is prevented from rotation. When the cassette is fitted in a printer, for example, the reel is shifted longitudinally against the force of the leaf-spring assembly, and the rotation preventing arm is moved away from the stub shaft so that the reel is allowed to rotate. The prevention of rotation is effective to eliminate unintentional slackening of the sheet-like medium.