Backlight assembly includes a plurality of light guide plates, a plurality of light modules, and a plurality of driving units separately in control of corresponding light modules which are configured at the incident sides of the LGPs. The lock device includes a helical gear rotated by the motor. A slicing scheme unit is arranged for determining a slicing scheme for pathologic examination of the specimen, based on the at least one parameter. A time delay in the transmission of the voice of the hearing user through the relay is of assistance to the assisted user in comprehending the communications session.