Magnetic tape reel having a positioning mark capable of being detected using a contactless detector, tape cartridge using the same, recording and reproducing apparatus for recording and reproducing information in the tape cartridge, and information recording and reproducing method thereof

A magnetic tape reel that has a plurality of gear teeth capable of engaging with a plurality of engagement gear teeth provided with a reel engaging portion of a recording and reproducing apparatus and upon which magnetic tape can be wound, the reel comprising:

• a hub portion including a cylindrical portion upon which the magnetic tape can be wound and the plurality of gear teeth;
• and
• a positioning mark capable of being detected using a contactless detector, the positioning mark being provided for aligning a specific gear tooth A from the plurality of gear teeth with a specific engagement gear tooth B from the plurality of engagement gear teeth,
• wherein the hub portion has a closed-end cylindrical shape, and
• the plurality of gear teeth are provided on an external surface of a base portion of the hub portion having a closed-end cylindrical shape,
• the magnetic tape reel further comprising:
• a first flange extending in a radial direction from a peripheral surface of one end of the hub portion;
• and
• a second flange extending in a radial direction from a peripheral surface of the other end of the hub portion that is closer to the base portion than the one end,
• wherein the positioning mark is provided on the external surface of the base portion of the hub portion, and
• the positioning mark is detected by a detection portion that is provided on the reel engaging portion of the recording and reproducing apparatus.