| 摘要 |
PURPOSE:To take and accurate measurement by irradiating an object of measurement with a scanning light directly, and photodetecting the resulting transmitted or reflected light or the projection image of the object by a photoelectric sensor. CONSTITUTION:When the projection image 4A of the object of measurement is passed through the photoelectric sensor 12, output signals (a) and (b) from sensor output terminals 13A and 13B are processed by difference arithmetic 38 to obtain a signal a-b, which are inputted to the 1st and the 2nd comparing circuits 20 and 22. Then, the circuits 20 and 2 generates output signals (c) and (d) when an input analog signal and the signal a-b vary from a high level to a low level and reset the signals (c) and (d) when they vary from the low level to the high level. An exclusive OR which inputs the signals (c) and (d) outputs a signal (e) to a pulse signal generator 34, which outputs a pulse signal (f) to an AND gate 32. The signal (a) from the sensor 12, on the other hand, is passed through an area signal generator 31 and a digital signal generator 30 a digital signal '1' to the gate 32. Then, the gate 32 detects the edge of the image 4A when the input signals are both '1'. |
