| 摘要 |
PURPOSE:To accurately detect only the intensity of an impact by holding the level of a high-frequency component contained in an acceleration sensor output when the acceleration sensor output exceeds a 1st level and the high frequency component of the sensor output exceeds a 2nd level. CONSTITUTION:The voltage signal Va of an acceleration sensor 1 is passed through an HPF17 to extract its high-frequency component, which is amplified 15 to become a voltage Ve; and the voltage is inputted to the positive terminal of a comparator 19, and also integrated by a LPF23 and inputted to the negative terminal. A diode 21, however, is connected to the negative terminal, so a reference voltage Vr1 is inputted to the negative terminal of the comparator 19 for a signal lower than the reference voltage Vr1 and the output signal is inputted for a signal higher than the voltage Vr1. The comparator 19 outputs an H-level pulse signal Vg within a range of Ve>Vf to open a switch 26, and the peak value of the signal Ve is held in a capacitor 27. This held voltage is converted by an A/D converter 28 into a digital signal Dd, which is read in a CPU29 to detect sound height data DP corresponding to the intensity of the impact. |
