| 摘要 |
PURPOSE:To make it possible to detect the edge of an article to be measured even if a sensor is moved at a high speed, by operating the sample holding circuit of a region signal generator at the rising time of the output signal of a first comparator by a one-shot pulse signal. CONSTITUTION:The output signals (a), (b) issued from the sensor output terminals 14A, 14B of a sensor 12 are operated by a differential operator 16 to be outputted as a signal (c). The signal (a) is inputted to the first comparator 24A of a region signal generator 18 and, when the signal (c) is larger than reference voltage V<+>Ref, a high level signal (d) is outputted to a one-shot pulse generator 25A which in turn outputs one pulse signal d' to a sample holding circuit 26A at that point of time. The circuit 26A holds the signal value at the final point of time of sampling when no signal d' is outputted. That is, because the start point of time of the holding of the signal is set to the falling point of time of one signal d' on the basis of the rising of the signal (d), the holding start of time is not delayed from a cross point. Therefore, even if the sensor 12 is moved at a first speed, the edge of an article to be measured can be detected certainly.
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