A bottom lighting module comprises a substrate, a nut, a first diffusion sheet, a support, a second diffusion sheet and at least one light-emitting diode. The computer system includes a first agent, a point to point half duplex interface coupled to the first agent and a second agent coupled to the first point to point half duplex interface. In one embodiment, the optimal field of view for a target object can be automatically selected with the use of a range finder. The walls that define the space in which the component including the internal circuit is housed may be of a minimum thickness required irrespective of resonance caused by vibrations of the speakers. The holder member supports the electrode member, and holds the cleaning member movable in parallel to a nozzle array direction in which the nozzles is arrayed in the head.