A spatial filtering adaptable for an interference wave that appears unsteadily can be implemented and also an interference canceling ability can be increased even in a condition that the interference wave does not steadily exist. A voltage difference compensating means is connected to each of the gate driver integrated circuits to compensate for voltage differences between the driving signals according to line resistance differences between the line-on-glass type signal lines. From this binary search table, an index into other structures stored in firmware is obtained that may be used to identify a target device. In this manner, the second device is unable to pass an unauthorized, or \u201cspoofed,\u201d management key block. The cavity is shaped to direct the gas flow without requiring the application of external electrostatic fields. The emitting elements may be provided by Spindt emitters, sharp or serrated metallic edges or carbon nanotubes.