A disk cartridge is disclosed in the Japanese Patent Application Laid Open No. 2003-109343. This disk cartridge includes a cartridge body formed from an upper shell and lower shell butt-joined to each other and having a first write/read opening formed in the lower shell, an inner rotor encased in the cartridge body, housing a disk as a recording medium and having a second opening corresponding to the first opening in the cartridge body, and a shutter mechanism disposed between the inner rotor and lower shell to uncover the first and second openings when the latter coincide with each other in conjunction with the rotation of the inner rotor.
In the disk cartridge, the inner rotor has formed at a part of the periphery thereof a gear portion which is exposed to outside the cartridge body. When the disk cartridge is loaded into a disk recorder and/or player, a rack gear provided at the latter is put in mesh with the gear portion of the inner rotor and the shutter mechanism uncovers the first and second openings as the inner rotor is rotated. Thus, write or read to or from the disk becomes possible.
Note here that to provide a small disk cartridge housing a small-diameter disk using the same recording format as used with a disk in the above-mentioned disk cartridge, the rack gear of the disk recorder and/or player, working as a shutter releasing mechanism, cannot be used. That is, when the small disk cartridge is loaded into the disk recorder and/or player destined for use with a disk cartridge having the standard size as disclosed in the above-mentioned Japanese Unexamined Patent Application Publication, it has to be loaded correspondingly to positions of an optical pickup and disk table because the latter are fixedly positioned.
Note here that in the above case, the gear portion of the inner rotor of the small disk cartridge will not be in mesh with the rack gear of the disk recorder and/or player, as the shutter releasing mechanism for the standard-size disk cartridge, namely, the rack gear cannot be used. A moving mechanism provided, if any, to move the rack gear for being in mesh with the gear portion of the loaded small disk cartridge will have a very complicated configuration. Therefore, for using such a small disk cartridge with the disk recorder an/or player destined for use with the standard-size disk cartridge, the shutter mechanism for the small disk cartridge has to be configured differently from that for the standard-size disk cartridge.