Patent ID: 6681178
Filing Date: 2004-01-20
Classification: G01C,G09B

Abstract:
A navigation device, comprising:a first control unit for setting a first position and a second position; a second control unit for reading first map data for searching a rough route from the first position to the second position from a recording medium; a route search processing unit for searching the rough route from the first position to the second position based on the read first map data; a pre-reading processing unit for pre-reading second map data, necessary for displaying a detailed map, from the recording medium; a data buffer for storing the pre-read second map data; a route guiding processing unit for providing a route guiding to the second position based on the stored pre-read second map data; a calculation unit for calculating at least one of a quantity of the stored pre-read second map data, indicative of a range of the route guiding that said route guiding processing unit can provide by using the stored pre-read second map data, and a ratio of the stored pre-read second map data, indicative of an amount of the stored pre-read second map data with respect to an amount of the second map data required to guide from the first position to the second position; and a notification unit for notifying at least one of the calculated quantity and the calculated ratio.