A wireless communication system may acquire specific information including identification information from each of access points. Two time thresholds provided by respective timers are used at the controlled device, a lower time threshold for determining the short activation and a higher time threshold for determining the long activation; the difference between the two time thresholds indicates a \u201cdead zone\u201d of no control action. The system includes an improved process path exchanging a detachable wafer carrying head with spindles at each processing point and conveying the detached wafer carrying heads in a rotary index table between processing points. Two- and three-dimensional embodiments are contemplated. A pressure control device controls pressure of the ink to satisfy the equation P1<P2\u2266P0, where P1 is the pressure of the ink at a meniscus surface inside the ink discharge port, P2 is the pressure of the ink at a surface of the porous member forming the inner wall of the ink discharge port, and P0 is an atmospheric pressure.