| 摘要 |
Electrooptical measuring device having a glass scale and a relatively displaceable scanning head which has at least three successive scanning gratings which are transparent in the manner of a window and are phase shifted by 120 DEG or 60 DEG relative to one another. The scanning gratings have the same grating grid and the same line width per graduation line as the glass scale. Each scanning grating is assigned a light-emitting diode and an electrooptical transducer at the same level. The grating grid (r) satisfies the relationship r = n .2x. The resolution x is 1 mu , the grating grid 6 mu and the line width 3 mu . Only one voltage value is tapped per sinusoidal curve at the transducer output, specifically in the middle region in the case of the largest change in voltage per displacement unit. An exactly sinusoidal optical contrast as a function of the displacement is therefore not a prerequisite for accurate measurement. Given good optical contrast, it is possible to double or quadruple the individual pulses, that is to say the measurement accuracy, by respectively tapping 2 and 4 voltage values per curve. The evaluating electronics are simple, light, small, inexpensive and insensitive to voltage fluctuations.
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