MEASURING INSTRUMENT FOR SWING SPEED

PURPOSE:To measure the swing speed of a swing body like a bat by calculating the integral value of acceleration with time as the speed. CONSTITUTION:An acceleration sensor 3 composed of a piezoelectric body has no directivity in a plane perpendicular to the lengthwise direction of the bat 1 and a voltage corresponding to variation in pressure operating on the piezoelectric body when the bat 1 is accelerated is led out to measure the acceleration. The output of the sensor 3 is inputted to an arithmetic circuit 4 through an A/D converter 10 to the integrated acceleration at each time with time. The output of the sensor 3 is passed through an inverting amplifier circuit 12 and only the fast oscillation component of the sensor output is passed through an HPF 13. Then, a diode 14 removes a negative signal component to trigger a one-shot multi-vibrator 15 with a positive signal component, and a waveform- shaped signal is inputted to the circuit 4 to calculate the integral value of acceleration with time from the start of a bat swing to the detection of an impact, so that the swing speed and speed at the moment of the impact are displayed 5.