| 摘要 |
<p>PURPOSE:To obtain a chopping wave output with a high linearity only by changing the patterns of slits by providing a fixed slit plate arranged on both sides of a rotary disk as opposed thereto with a plurality of first and second slits with their phases shifted by 90 deg.. CONSTITUTION:A fixed slit plate 7 is arranged on one side of a rotary disk 5 as opposed thereto and a photodetector 8 is provided below the slit plate 7. A plurality of first and second slits with their phases shifted by 90 deg. are formed in the plate 7. A light emitting element 11 is provided on the other side of the disk 5. Light emitted from the element 11 reaches the photodetector 8 via the light transmitting portion of the disk 5 and the first and second slits. Output waveforms produced in the photodetector 8 are such that output signals generated by the light passing the first and second slits have waveforms A and B, respectively, said waveform B having a phase shifted by 90 deg. from that of the waveform A. When both the waveforms A and B are composed in the photodetector 8, an analog chopping waveform with a good linearity such as a waveform C can be obtained. Further, when the light receiving mask pattern of the slits has a construction wherein phases are shifted by 90 deg., the same effect can be obtained.</p> |
