| 摘要 |
PURPOSE:To detect only vehicles which pass just above the devide, by using a magnetic detector havin biaxial components which make >=45 deg. on the same plane. CONSTITUTION:A magnetic detector 1 has two detecting windings wound >=45 deg. to each other and detects magnetic field components of two directions. The output of the detector 1 is appplied to detecting circuits 4 and 4' through amplifying circuits 3 and 3' to take out signals where the voltage output of a constant level due to the earth magnetism and the voltage corresponding to the variance of the magnetic field for passage of a vehicle are superposed, and these signals are applied to waveform detecting circuits 5 and 5' and differentiating circuits 9 and 9'. Magnetic variance signals due to the vehicle are detected by circuits 5 and 5' and are applied to level detecting circuit 7 and 7' through absolute value circuits 6 and 6', and outputs are obtained only when these signals are higher than set levels. Outputs of circuits 7 and 7' are connected to AND circuits 8 and 8' and OR circuits 13 and 13'. Waves differentiated by circuits 9 and 9' are inputted to counting circuits 12 and 12' through absolute value circuits 10 and 10' and level detecting circuits 11 and 11'. The counting circuit 12 counts differentiated wave pulses, and the circuit 12 issues the output when it counts four pulses at least. |
