The present invention relates to a shutter opening mechanism of a data recording/reproducing device and, more specifically, to a shutter opening mechanism used for opening a shutter of an optical disk which is inserted into the data recording/reproducing device. 
A conventional data recording/reproducing device includes a cartridge holder that holds a disk cartridge and that is driven to load and unload the disk cartridge from the data recording/reproducing device. 
FIG.  2 is a perspective view of a disk cartridge 11.  The disk cartridge 11 includes a shutter 12, a head access window 13, and a motor access window 14.  The shutter 12 includes a slot 15 and is biased by a spring (not shown) in a direction B. The disk cartridge 11 houses an optical disk 8 supported on a hub 9. 
The cartridge holder conventionally includes an arm that engages with the slot 15 in order to open the shutter 12 as the disk cartridge 11 is loaded into the disk drive. 
FIG.  1 is an exploded view of an end of a conventional arm 245.  The end of the arm 245 includes a circular hole 245A. Two rollers 248A abut either side of the hole 245A. Each roller 248A also includes a circular hole 248B coaxially aligned with the hole 245A but having a radius that is slightly smaller than that of the hole 245A. A pin 249 is inserted through the holes 248B and the hole 245A. The pin 249 has a cylindrical shape with a radius that is smaller than the radius of the hole 245A, but marginally larger than that of the holes 248B. Accordingly, the pin 249 is forced into the holes 248B such that, after insertion, the rollers 248A remain in a fixed position in relation to the pin 249, but the pin 249 rotates in the hole 245A.
However, since the pin 249 is inserted into the holes 248B by force, the radius of the holes 248B may increase due to residual stress and friction during rotation of the pin 249 and rollers 248A. Consequently, the pin 249 may be released, such that the pin 249 and rollers 248A may fall off of the arm 245.