Patent ID: 6286776
Filing Date: 2001-09-11
Classification: G11B

Abstract:
A magnetic tape cassette including, a cassette main body (324) having an opening (222) at a front part, top lid guide grooves (333) formed on both lateral side portions of said cassette main body, and inner lid guide grooves (235) formed on inner lateral side portions of the cassette main body,a pair of reels (223, 225) disposed inside said cassette main body and attached so as to be rotatable with a magnetic tape (205) wound therearound, anda lid unit (227) for covering said opening,wherein said lid unit (227) comprises:an outer lid (329) includingan outer lid plate (329a) that covers a front side of said magnetic tape (205) that is suspended over said opening,side plate portions (329b) extending from both sides of said front lid plate (329a) and being rotatably supported by both lateral side portions of said cassette main body, andpins (329c) protruded from the inner wall surfaces of said side plate portions (329b) and rotatably fitted on both lateral side portions of said cassette main body in such a manner that said outer lid (329) is rotatable with respect to said cassette main body about said pins;a top lid (303) includinga top lid plate (303a) covering an area above said magnetic tape which is suspended over said opening, said top lid plate (303a) being provided with arm portions (303c) which extended from both ends of said top lid plate,outer lid linking portions (303b) rotatably engaging both ends of said top lid plate at the front edge side thereof to a top edge of said outer lid plate, andtop lid slide pins (303d) protruded from said arm portions (303c) and engaged with said top lid guide grooves (333) of said cassette main body (324) so as to be slidable relative to said cassette main body; andan inner lid (231) including,an inner lid plate (231a) covering a rear side of said magnetic tape which is suspended over said opening,top lid linking portions (231b) engaging a top edge of said inner lid plate (231a) with said top lid plate (303a) so as to be rotatable relative to each other, andinner lid slide pins (231c) protruded from both ends of a bottom edge of said inner lid plate (231a) and engaged with said inner lid guide grooves (235) so as to be slidable relative to said cassette main body;wherein at least a portion of said top lid slide pins (303d) of said top lid (303) that is brought in sliding contact with the sliding surfaces (333a) of said top lid guide grooves (333) have a sectional configuration which is formed by a curved line which has a normal that is tilted forward in the direction of the movement of said top lid slide pins (303a) as compared with a normal of said sliding surfaces (333a) at the contact points between the top lid slide pins and the top lid guide grooves.