Disc cartridge

Claim 2

A disc cartridge comprising: a cartridge case (1) for encasing therein a recording medium disc, said cartridge being made of plastic; a shutter (6) slidably mounted on said cartridge case for opening and closing at least one head insertion hole (5) formed in said cartridge case; and a guide portion (G) formed in a front edge of said cartridge case (1) in an insertion direction toward a recording and reproducing apparatus, characterized in that a slider (4) is slidingly engaged with said guide portion (G), said slider (4) being formed of plastic, said shutter (6) being fixed to said slider (4).

Claim 3

The disc cartridge according to claim 1, wherein said shutter (6) includes a head portion (13) slidingly moving along said front edge of said cartridge (1); opening and closing plate portions (11) for opening and closing said head insertion hole (5) for write and read operations, said opening and closing plate portions (11) being extended from both sides of said guide plate portion (13); and guide end plate portions (12) moving along retainer plates (8) provided on said cartridge (1), said guide end plate portions(12) being formed at lower ends of said opening and closing plate portions (11), wherein said opening and closing plate portions (11) are expanded with their intermediate portions being raised from sliding surfaces on the cartridge (1).

Claim 4

The disc cartridge according to claim 2, wherein the retainer plates (8) for retaining said guide end plate portions (12) of said shutter (6) are lowered in level from surfaces of said cartridge case (1).

Claim 5

The disc cartridge according to claim 1, wherein a peripheral wall of said head insertion hole is chamfered.

Claim 6

The disc cartridge according to claim 1, wherein a spindle hole (4) into which a spindle for rotating the disc is inserted is formed in a central portion of said cartridge, said head insertion hole being continuous with said spindle hole (4) substantially in a radial direction, wherein parts of a connecting portion between said head insertion hole and said spindle hole (4) are projected to an inner side of the two holes in the lateral direction in confronted relation with each other, the projected ends being chamfered.

Claim 7

The disc cartridge according to claim 2, wherein at least one engagement recess portion (18) is formed in said slider (4); a screw hole (55) is formed in said engagement recess portion (18); an engagement projection (59) for engaging with said engagement recess portion (18) is provided in the connecting portion between the shutter (6) and the slider (14); an opening (59a) is formed in the engagement portion; when said engagement projection (59) is engaged with said engagement recess portion (18), a fastening screw (53) having an enlarged head (52) and a slanted surface (60) is inserted into said screw hole (55) of said engagement recess portion (18) through said opening of said engagement portion while said slanted surface (60) around said enlarged head of said fastening screw is brought into contact with said opening (59a).

Claim 8

The disc cartridge according to claim 6, wherein both sides of said slider (14) corresponding to said screw hole (55) are slightly cut away to form recesses (65).

Claim 9

The disc cartridge according to claim 1, wherein said shutter (6) is coated with UV curing resin.

Claim 10

The disc cartridge according to claim 1, wherein a receiving hole (19) engaged with an opening and closing pin (P1) for opening and closing the shutters (6) is formed in said slider ( 14); a cutout (27) through which said opening and closing pin (P1) is inserted into said receiving hole (19) is formed in said shutter (6) at a position corresponding to said receiving hole (19); and a head portion (13) of said shutter (6) is fixed to said slider (14) under the condition that a side face (F2) on the drive side with which the opening and closing pin (P2) received in the receiving hole (19) of the slider (14) is brought into contact is protruded from the cutout (27) on the drive side of said shutter (6) in a direction opposite a direction in which the opening and closing pin (P1) drivingly moves the shutter (6).

Claim 11

The disc cartridge according to claim 1, wherein a return coil spring (10) for biasing said shutter (6) through said slider (14) to a position where said shutter (6) closes said head insertion hole (5) is provided within a receiving space (S) at a corner of the oartridge case (1), said return coil spring (10) being composed of an elastic wire coiled portion (41) and two arms extended from said coiled portion (41); and when said return coil spring (10) is received in the corner space (S), one of the arms is composed of a first extension portion (43a) extending substantially along a circumferential periphery of the disc from said coiled portion (41) and a second extension portion (43b) bent from said first extension portion toward a front wall in the insertion direction for the recording and reproducing apparatus for the cartridge, a distal end of said second extension portion (43b) being engaged with a tip end of said slider (14), and the other arm is composed of a third extension portion (42a) extended from said coiled portion (41) toward the front wall and a fourth extension portion (42b) bent form said third extension portion (42a) toward the front wall of said cartridge case, a distal end of said fourth extension portion (42b) being engaged with the front wall of said cartridge case.

Claim 12

The disc cartridge according to claim 1, said a radius of curvature of a bent portion between said third extension portion (42a) and said fourth extension (42b) portion is in the range of 0.8 to 3mm.

Claim 13

The disc cartridge according to claim 10, wherein a recess portion (33) for receiving the distal end of said second extension portion (43b) of said return coil spring (10) is formed in the tip end of said slider, said recess portion being provided with a projection (31a) for guiding said distal end of said return coil spring (10) into said recess portion (33) and for preventing the distal end once introduced into said recessed portion (33) from being pulled apart from the recess portion (33).

Claim 14

The disc cartridge according to claim 1, wherein a head portion (13) of said shutter (6) projects from an upper portion of a body plate of said shutter (6) in the lateral direction to form a projection (6d), an opening and closing pin insertion hole (27) for an opening and closing said shutter (6) is formed in said projection (6d), and a distance (S) between a defining side, extending in a moving direction of the shutter (6), of the guide recess portion (250) of the cartidge case receiving and projection of said shutter and an opposite side of said head portion in confronted relation with said defining side is sufficiently increased, thereby avoiding the sliding contact between these slides.