| 摘要 |
PURPOSE:To enable the detection of the variation and direction of rotation with only one optical path, by arranging a rotary slit plate having a plurality of slits different in the transmission wavelength and a fixed slit plate in an light course to detect the quantity and wavelength of light received at a light receiving section. CONSTITUTION:A rotary slit plate 11 rotating with a rotor and a fixed slit plate 10 are arranged between light emitting and receiving sections. The rotary slit plate 11 is provided with a plurality of slits 1-3 different in the transmission wavelength. At the light receiving section, for example, a plurality of light receiving elements I and II different in the light receiving sensitivity characteristic to detect a light receiving power. With such an arrangement, as the rotor is rotated, only the components with the wavelength passing through slits 1-3 of the rotary slit plate 11 synchronizing the slits of the fixed slit plate 10 are detected with light receiving elements I and II to capture changes in the outputs of the elements thereby enabling the detection of the variation of the rotor and the direction of the rotation. |
