Patent ID: 6484093
Filing Date: 2002-11-19
Classification: G01C

Abstract:
A communication route guidance system wherein an information center transmits route information to a mobile unit for guiding said mobile unit from its current position to a destination, in response to a request from said mobile unit,said information center comprising: first communication means for transmitting and receiving data to and from said mobile unit; first memory means for storing first road data; first route search means for searching said stored first road data to obtain first route guidance data for guiding said mobile unit from said current position to said destination, each time said information center receives said request from said mobile unit, said current position and said destination being transmitted from said mobile unit through said first communication means; and data dividing means for dividing said first route guidance data into a plurality of data segments, each data segment being usable in said mobile unit as an independent item of route information providing guidance from a near end of a route segment corresponding to a data segment to the opposite, remote end of the route segment; and said mobile unit comprising: second communication means for transmitting and receiving data to and from said information center; second memory means for storing second road data; second route search means for searching said second road data to obtain second route guidance data for guiding said mobile unit from said current position to said destination; third memory means for storing at least one data segment transmitted from said information center through said first and second communication means; sensor means for detecting whether data communication with said information center through said first and second communication means is available; and route guidance means for guiding said mobile unit to said destination in accordance with at least one of said second route guidance data and said at least one data segment stored in said third memory means, said route guidance means guiding said mobile unit to said destination in accordance with said second route guidance data when said sensor means detects that data communication between said mobile unit and said information center is not available.