Method of making magnetic disk cartridge

Claim 1

A method of making a magnetic disk cartridge by positioning a disk-like magnetic recording medium provided at the center with a circular hole between an upper hub and a lower hub concentrically to said upper hub and said lower hub, and fixing said upper hub, said lower hub and said magnetic recording medium to each other by use of a double-faced adhesive member positioned between said upper hub and said magnetic recording medium, wherein the improvement comprises: (i) positioning at least three guide bars resiliently mounted for axial movement, said guide bars being projected so as to define a circle circumscribed thereabout having the diameter of said circular hole and centering said magnetic recording medium by contacting the inner circumference of said circular hole of said magnetic recording medium with said guide bars, (ii) providing a plurality of through holes in a medium-grasping portion of said lower hub, the latter serving for engagement with a disk-rotating shaft of a recording and reproducing apparatus, said through holes being dimensioned for tight insertion of said guide bars thereinto and positioned at equal distances from the center of said lower hub, (iii) inserting said guide bars into said through holes of said lower hub and supporting said lower hub on said guide bars, (iv) engaging the inner circumference of said circular hole of said magnetic recording medium with said guide bars to center said magnetic recording medium relative to said lower hub and mounting said magnetic recording medium on said lower hub, and (v) thereafter pushing the end portions of said guide bars by lowering said upper hub to which said double-faced adhesive member is secured, thereby moving said guide bars away from the surface of said magnetic recording medium and securing said double-faced adhesive member to both said magnetic recording medium and said lower hub.

Claim 2

A method of making a magnetic disk cartridge by positioning a disk-like magnetic recording medium provided at the center with a circular hole between an upper hub and a lower hub concentrically to said upper hub and said lower hub, and fixing said upper hub, said lower hub and said magnetic recording medium to each other by use of a double-faced adhesive member positioned between said upper hub and said magnetic recording medium, wherein the improvement comprises: (i) positioning at least three guide bars resiliently mounted for axial movement, said guide bars being projected so as to define a circle circumscribed thereabout having the diameter of said circular hole and centering said magnetic recording medium by contacting the inner circumference of said circular hole of said magnetic recording medium with said guide bars, (ii) providing a plurality of through holes in a medium-grasping portion of said lower hub, the latter serving for engagement with a disk-rotating shaft of a recording and reproducing apparatus, said through holes being dimensioned for tight insertion of said guide bars thereinto and positioned at equal distances from the center of said lower hub, (iii) inserting said guide bars into said through holes of said lower hub and supporting said lower hub on said guide bars, (iv) engaging the inner circumference of said circular hole of said magnetic recording medium with said guide bars to center said magnetic recording medium relative to said lower hub and mounting said magnetic recording medium on said lower hub, and (v) thereafter pushing the end portions of said guide bars by lowering said upper hub to which said double-faced adhesive member is secured, thereby moving said guide bars away from the surface of said magnetic recording medium and securing said double-faced adhesive member to both said magnetic recording medium and said lower hub.