On-board navigation apparatus

In an on-board navigation apparatus having a plurality of sensors for determining position and a controller for correlating said position with map coordinates and subsequently displaying said position and a map image containing said coordinates, the improvement comprising:

• reading/storing means for reading only block data of a block containing a display center point and block data of blocks adjoining thereto from a storage medium where image data forming one consecutive screen is stored for each piece of block data corresponding to a block on the screen, and storing the read-out pieces of block data separately into a buffer memory, said buffer memory being divided into a plurality of N discrete storage buffers, where N is an integer;
• and
• display control means for acquiring display data forming a display screen with the display center point as a center from said storage buffers and performing a display operation on the basis of the display data, said display control means having a display buffer memory for temporarily storing the display data so as to permit said display operation to be carried out on the basis of the display data.