Patent ID: 7676278

Claim:
A transport mechanism in a library apparatus, comprising: a first mobile carrier accessible to individual cells defined in a storage in the library apparatus, the first mobile carrier configured to move along a first path in the library apparatus; a second mobile carrier accessible to the individual cells, the second mobile carrier configured to move along a second path at least partially wrapping over the first path in the library apparatus; a first controller circuit disposed in the library apparatus, the first controller circuit being connected to a driving motor incorporated within the first mobile carrier for supplying a driving signal to the driving motor; a second controller circuit disposed in the library apparatus, the second controller circuit being connected to a driving motor incorporated within the second mobile carrier for supplying a driving signal to the driving motor within the second mobile carrier, the second controller circuit being connected to the driving motor in the first mobile carrier for supplying a driving signal to the driving motor in the first mobile carrier; and a library controller connected to a host computer outside the library apparatus, the library controller connected to the first controller circuit and the second controller circuit, the library controller monitoring an occurrence of a defect in the first controller circuit during an operation of the first mobile carrier, the library controller instructing the second controller circuit to supply the driving signal to the driving motor in the first mobile carrier to convey the first mobile carrier to a position outside the second path of the second mobile carrier when the defect has occurred in the first controller circuit, wherein the library controller is configured to monitor replacement of the first controller circuit, to switch on the first controller circuit when the library controller detects the replacement of the first controller circuit, to drive the second mobile carrier to a position outside the first path of the first mobile carrier, and to instruct the first controller circuit to diagnose the first mobile carrier.