Patent ID: 6944557
Filing Date: 2005-09-13
Classification: G06F

Abstract:
1. An ultrasonic length measuring apparatus comprising: a transmission unit for transmitting an ultrasonic wave signal; at least one receiving unit for receiving the ultrasonic wave signal and converting it into an electrical signal; a timing detection unit for measuring a number of times a waveform of the ultrasonic wave signal received by the receiving unit crosses a predetermined threshold value, for detecting a first crossing point corresponding to the ultrasonic wave signal crossing the predetermined threshold value a first time, and for detecting a crossing timing corresponding to a second crossing point when the ultrasonic wave signal crosses the predetermined threshold value a predetermined number of times after the first crossing point; a time measuring unit for measuring a time period from a start of transmission of the ultrasonic wave signal by the transmission unit to the crossing timing detected; and a length measuring unit for calculating a length based on the measured time period.