| 摘要 |
PURPOSE:To perform measurement accurately even when a material is conveyed at high speed, by detecting the fore end of the material by means of a TV camera, and by modifying an error in measurement of the speed of the material on the basis of a difference in the number of scan lines detected in an odd-number field and an even-number field thereof. CONSTITUTION:A conveyor mechanism 1 conveys a material 2, and when the rear end of the material 2 reaches a position detector 4 as in a condition A, the detector 4 outputs a detection signal, a camera controller 6 delivering a signal of instruction to start pickup to a TV camera 8. The material 2 is located at a position in a condition B on the occasion, and the camera 8 picks up the fore end of the material 2, subjecting a signal of a scan line in an odd-number field to A/D conversion and inputting same to a microcomputer (MC) 10 of an arithmetic means. Next, it subjects a signal of the scan line in an even-number field to A/D conversion and inputs same to MC 10, while the material 2 is transferred to a position in a condition C on the occasion. MC 10 detects a horizontal scan line of the fore end of the material 2 at this time from a change in luminance of a video signal subjected to A/D conversion, and subtracts from an apparent length L1 a modified value measured excessively due to delay in a measuring time, so as to perform accurate measurement.
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