Vehicular dialogue interface with centralized commander

A vehicular dialogue interface comprising:

• a display for displaying letters;
• and
• a centralized commander comprising
• a decision switch installed at the center of the commander and actuated by pressing operation to output predetermined operation command;
• a first scan switch actuated by independent pressing operation relative to pressing operation of the decision switch to output directional operation command corresponding to pressing position, and operable for an inching scan of the letters in a first direction;
• a second scan switch surrounding the first scan switch and actuated by rotating operation to output signal corresponding to rotation angle, and operable for a traverse scan of the letters in a second direction different from the first direction;
• a first tact switch installed under the decision switch and detecting pressing operation of the decision switch;
• and
• a second tact switch installed under the first scan switch and detecting pressing operation of the first scan switch;
• wherein the first scan switch is disc-shaped and surrounds the decision switch.