Patent ID: 8749405

Claim:
A navigation system comprising: an input device configured to input an input scale value; a display device configured to display road map information according to a selected display scale value; and a processor device which is set and coupled with the input device and the display device such that a number of enterable input scale values is larger than a number of the selectable display scale values, and wherein the display scale value is determined by: setting the input scale value as a display scale value when the input scale value is equal to a selectable display scale value, determining a display scale value nearest to the input scale value when the input scale value is not equal to a selectable display scale value, setting the determined display scale value as a display scale value when the determined display scale value is not equal to the last selected display scale value, setting the next-larger display scale value from the determined display scale value as the display scale value when the determined display scale value is equal to the last selected display scale value and the input scale value is larger than the last selected display scale value, and setting the next-smaller selectable display scale value from the determined display scale value as a display scale value when the determined display scale value is equal to the last selected display scale value and the input scale value is smaller than the currently selected display scale value.