If the boundary value of a velocity scale set in a case where the information indicating the velocity of the moving body is displayed on a liquid crystal panel is less than a threshold value, the frequency of pulses used in pulse-width control is set to 20 kHz in such a manner that noise ascribable to the pulses for pulse-width control will not be displayed on the liquid crystal panel. If the boundary value of the velocity scale is equal to or greater than the threshold value, then the frequency of pulses used in pulse-width control is set to 200 Hz in such a manner that noise ascribable to the pulses for pulse-width control will reside at a position remote from the information indicative of velocity.
