| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power consumption by selectively supplying the power to a display device. SOLUTION: A CPU 6 computes the running bearing of a vehicle based on the output data of a bearing sensor 1 at a constant time interval by time division when the vehicle is running, obtains the present position of the vehicle from the running distance and the running bearing by the division of a distance sensor 2, collects the map data in a specified region from a memory device 10, stores the data in a RAM 8 temporarily, supplies the data into a display device 12 and drives a power supply relay 11 through a driving circuit 9 so as to supply the power to the memory device 10 only when the map data are read out of the external memory device 10 furthermore. Then, the power is selectively supplied to the display device 12 through a power supply switch 17 from a power supply line L. The user turns off the power supply switch 17 when the display of the map on a display 13 is not required and can stop the power supply to the display device 12. |
