A library apparatus functions as an external storage apparatus with a large capacity. It generally stores, for example, thousands of cartridges, in each of which a magnetic tape is accommodated as a storage medium, in a storage unit in a locker. The storage medium in each cartridge is automatically accessed to, for example, read and write data.
In addition to the storage unit in which cartridges are stored as described above, the library apparatus includes mechanisms, such as a cartridge access station (CAS), a direct entry/exit (DEE), and a forced exit station (FES), which are used to insert cartridges from the outside into the library apparatus or eject them from the library apparatus to the outside, a plurality of magnetic tape drive units (MTUs) used to access the storage media (magnetic tapes) in the cartridges to, for example read recorded data and write data to be recorded, and an automatic cartridge transporting robot, referred to below as an accessor (ACC), which is used to automatically transport cartridges among the storage unit, the cartridge entry/exit mechanisms, and the MTUs.
When this type of library apparatus receives a request to access a certain cartridge from a high-end unit or the like, the accessor moves to the storage unit, searches for the cartridge, transports the cartridge, which is being grasped by a hand mechanism included in the accessor, to the relevant MTU, and inserts the cartridge into the MTU. Then, the MTU performs processing for the storage medium (magnetic tape) in the cartridge. Upon completion of the processing, the cartridge is ejected from the MTU and is grasped again by the hand mechanism. The cartridge is then transported to the storage unit by the accessor and is placed at the correct position.
In addition to the hand mechanism that grasps a cartridge, the accessor includes a transport unit that transports the hand mechanism from a cell, in which the cartridge is placed, in the storage unit to the insertion opening of the MTU. The hand mechanism includes a grasping mechanism that grasps a cartridge and another mechanism that inserts a cartridge into a cell or the MTU through its opening and takes out the cartridge from there through the opening. The transport unit includes mechanisms that move the hand mechanism vertically and horizontally in the library apparatus.
Japanese Laid-open Patent Publication Nos. 2005-93000 and 7-141124 are examples of related art.
With this type of conventional general magnetic tape auto loader, however, the accessor has a driving mechanism used as the grasping mechanism to open and close a member that grasps a cartridge, another driving mechanism used as the transport unit to move the hand mechanism vertically, and another driving mechanism used as the transport unit to move the hand mechanism horizontally, so the structure of the magnetic tape auto loader is complex. Accordingly, the manufacturing cost of the magnetic tape auto loader is increased and it is also difficult to reduce its size. Another problem is that many driving motors are used to achieve these driving mechanisms, increasing power consumption.