| 摘要 |
PURPOSE:To prevent flaws and dust on the surface of a long-sized running material from being detected erroneously, by opening a gate only at the detection time of a mark in case that this material is marked to graduate and measure the length of it. CONSTITUTION:Marks 2 are applied onto the surface of a running material by a mark applier 3, and marks moved just under sensors 7a and 7b are detected by them. Simultaneously with the mark detection due to the sensor 7b, the applier 3 applies the next mark. The interval of time between detection signals of two sensors is measured by a circuit 9, and a running speed is obtained on the basis of a length ls between sensors by a calculator 10. A length li between marks is obtained on a basis of the running speed and the interval of time between applications. Three gate signals (a), (b), and (c) are obtained from the speed signal by a DA converter 13, a VF converter 14, and a frequency selector 15, and AND between these signals and a pulse from a monostable multivibrator 16 which is triggered by the detection signal is operated in an AND17 to obtain a gate pulse for mark detection. Gates 17a and 17b are controlled by this gate pulse to detect only the mark signal. |
