Magnets for seeking provided for the base and magnets for focusing provided for a carriage are so arranged that they are shifted perpendicularly relative to each other. The very high-speed convoluting air discharge into a vortex cone causes a first separation of the Air gas components, by stratifying into heavier, medium and lighter components, where in the heavier and lighter components are non-combustible, inert gases and the medium is a combustible gas. Accordingly, fast association between the STA and the AP can be achieved by a simplified authentication procedure without repeating a full authentication procedure. The predetermined drop volumes include non-print drops of a unit volume V0, and print drops having volumes that are integer multiples of the unit volume, mV0, wherein m is an integer greater than 1.