PURPOSE: To elevate measuring accuracy by providing two optical sensors at a specified interval along the running direction of a filamentous body to output a pair of pulse detection signals positive and negative in the direction each time marks pass.
CONSTITUTION: A fishing line 2 is fitted with optically detectable marks 2a as formed by applying a white paint larger in the reflectance than the surface of the body by a specified length (l) at a fixed interval and a measuring device 1 is provided with a sensor head 3 to optically detect these optical marks 2a passing. Each time the marks 2a pass through the sensor head 3, a pair of detection signals comprising a positive pulse signal Pa corresponding to a first detection voltage Va and a negative pulse signal Pb corresponding to a second detection voltage Vb are outputted. Since a fluctuation component won't appear as output voltage Vc as inputted into a differential amplifier as identical phase component even when the levels of the detection voltage Va and Vb fluctuate with the vibration of the line in a guide hole 4a. Thus, the signal-to-noise ratio of the detection signal can be elevated.
KAWAAI SADAYUKI
TSUTSUMIUCHI MANABU
| JPS551762B2 | 1980-01-17 | |||
| JPS53103759A | 1978-09-09 |