| 摘要 |
PROBLEM TO BE SOLVED: To enable a moving body detecting system to accurately detect the distance of approach of a vehicle by using magnetic sensors which detect magnetic fluxes in a plurality of directions while suppressing the power consumption of the sensors to low levels. SOLUTION: The electric power of a secondary battery 20 is supplied to a vibration sensor 12 which consumes a small quantity of electric power and, when the vehicle approaches, the sensor 12 detects an oscillation value. When the oscillation value is at or higher than a fixed level, electric power is supplied from the battery 20 to horizontal and vertical magnetic sensors 8 and 10 which consume large quantities of electric power, because the vehicle approaches a prescribed distance from the moving body detecting system. Consequently, the sensors 8 and 10 detect horizontal and vertical magnetic fluxes Bx and By caused by the magnetism from the vehicle. A CPU 16 finds the distance of approach of the vehicle by calculating the absolute vector sum value Bz of the magnetic fluxes Bx and By from the fluxes Bx and By. The distance of approach of the vehicle found from the detected values of the fluxes Bx and By is transmitted from a Tx circuit 18 to a control office 3 by radio. Upon receiving the distance, the information on the distance of approach of the vehicle is displayed on the screen of a personal computer in the office 3. |
