A system and method of selecting and viewing communication traffic transmitted over an optical channel selected from among a plurality of possible channels without disrupting the communication traffic occurring over the selected channel or other channels is presented. When a nozzle that discharges black ink becomes unable to properly eject ink, cyan, magenta, and yellow inks are ejected from respective nozzles to the discharge area on the recording medium to which the defective nozzle should eject ink. The first comb-tooth electrode includes a plurality of first electrode teeth each having a first conductor, an insulator and a second conductor laminated in the direction of the oscillating motion, where the first conductor and the second conductor are electrically connected with each other. On the other hand, the second initialization-vector generation unit outputs the data with a size of 16 bytes to a decryption unit as an initialization vector IV. The passage of an electrical current, through two conducting lines commands a change in position of the mobile element of the magnetic microswitch situated at the intersection of the two conducting lines.