| 摘要 |
PURPOSE:To detect easily with a simple constitution the rotating angle of a substrate by detecting an angle acceleration applied from the external part to the substrate. CONSTITUTION:A weight 2, which reacts to the angle acceleration applied to the substrate 1, is provided, and the reticles 33, 43, 55 and 57, which extend in correspondence to the moving of the weight 2, are provided. The modulated light is introduced to the reticles 33, 43, 55 and 57, the transmitted light of the reticles 33, 43, 55 and 57 corresponding to the moving of the weight 2 is detected by a light receiving device 10, and a modulating frequency signal is extracted by a filter 11 from during the detecting output. Next, an oscillator 12 generates the frequency signal in proportion to the modulating frequency signal level and the counting part 13 detects the signal. By integrating hourly an angle acceleration of the substrate 1 twice by integrating devices 14 and 15 from the frequency value, the angle speed and further, the rotating angle are obtained and the azimuth of the substrate 1 can be detected.
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