Flexible magnetic disc cassette

Claim 1

A magnetic disc cassette comprising: a magnetic disc; a casing for enclosing said magnetic disc therein and including a head access opening; and a shutter provided on said casing and slidably moveable between an operating position at which it exposes said head access opening and a non-operating position at which it covers said head access opening; said shutter including substantially rectangular upper and lower plates and a side plate which joins said upper and lower plates along respective first edges thereof with a predetermined spacing therebetween so that said shutter has a generally U-shaped cross section within which said casing is fittingly received; at least one of said upper and lower plates having a shutter opening through which said head access opening is exposed for insertion of a head when said shutter is in said operating position; said upper plate, said lower plate and said side plate of said shutter being integrally molded from a synthetic resin material so as to have said U-shaped cross section; and both said upper and lower plates having second edges opposed to the respective first edges which closely approach each other and are separated by less than said predetermined spacing when said shutter is removed from said casing, whereby said first edges of said upper and lower plates are biased toward said casing when said shutter is fitted onto said casing.

Claim 4

A method for manufacturing a shutter for a magnetic disc cassette having a magnetic disc and a casing for enclosing said magnetic disc therein and including a head access opening, said shutter being provided on said casing to be slideably moveable between an operating position at which it exposes said head access opening and a non-operating position at which it covers said head access opening, said shutter including substantially rectangular upper and lower plates and a side plate which joins said upper and lower plates along respective first edges thereof with a predetermined spacing therebetween so that said shutter has a generally U-shaped cross section within which said casing is fittingly received, at least one of said upper and lower plates having a shutter opening through which said head access opening is exposed for insertion of a head when said shutter is in said operating position, said upper plate, said lower plate and said side plate of said shutter being integrally molded from a synthetic resin material so as to have said U-shaped cross section and both said upper and lower plates having second edges opposed to the respective first edges which closely approach each other and are separated by less than said predetermined spacing when said shutter is removed from said casing, whereby said first edges of said upper and lower plates are biased toward said casing when said shutter is fitted onto said casing; said method comprising the steps of: defining an internal space within said U-shaped cross section formed by said upper, lower and side plates of said shutter by inserting a first metal mold therein; defining outer surfaces of said plates by bringing a second metal mold into spaced engagement with said first metal mold, the volume between said first and second molds corresponding to said shutter; flowing said synthetic resin material into said volume between said first and second molds to form said shutter; and separately controlling the temperatures of said first and second molds so as to cause said second edges of said upper and lower plates to closely approach each other at less than said predetermined spacing after formation and removal of said shutter from said molds.

Claim 5

A method for manufacturing a shutter for a magnetic disc cassette having a magnetic disc and a casing for enclosing said magnetic disc therein and including a head access opening, said shutter being provided on said casing to be slideably moveable between an operating position at which it exposes said head access opening and a non-operating position at which it covers said head access opening, said shutter including substantially rectangular upper and lower plates and a side plate which joins said upper and lower plates along respective first edges thereof with a predetermined spacing therebetween so that said shutter has a generally U-shaped cross section within which said casing is fittingly received, at least one of said upper and lower plates having a shutter opening through which said head access opening is exposed for insertion of a head when said shutter is in said operating position, said upper plate, said lower plate and said side plate of said shutter being integrally molded from a synthetic resin material so as to have said U-shaped cross section and both said upper and lower plates having second edges opposed to the respective first edges which closely approach each other and are separated by less than said predetermined spacing when said shutter is removed from said casing, whereby said first edges of said upper and lower plates are biased toward said casing when said shutter is fitted onto said casing; said method comprising the steps of: defining an internal space within said U-shaped cross section formed by said upper, lower and side plates of said shutter by inserting a first metal mold therein; defining outer surfaces of said plates by bringing a second metal mold into spaced engagement with said first metal mold, the volume between said first and second molds corresponding to said shutter; flowing said synthetic resin material into said volume between said first and second molds to form said shutter; and separately controlling the temperatures of said first and second molds so as to cause said second edges of said upper and lower plates to closely approach each other at less than said predetermined spacing after formation and removal of said shutter from said molds.