| 摘要 |
PURPOSE:To obtain a desired amount of light, reduce power consumption and to obtain a stable length measuring action by a method wherein length measuring light is obtained from the light source of a self-luminous substance. CONSTITUTION:Length measuring light 100 supplied to slit plates 10, 12 is obtained from the light source of a self-luminous substance 14. A white sheet material 16 having a high reflection coefficient is coated with the self-luminous substance 14, which is attached to the rear surface of the main slit plate 10. Light receiving elements 18, 20 are arranged oppositely to a fluorescent portion upon which the length measuring light is incident through slits 10a, 12a, 12b on the light receiving side of the plates 10, 12. Therefore, this makes it possible to detect a signal corresponding to the variation of the amount of the length measuring light 100 in different phase from the elements 18, 20, the length measuring light being made to pass through the plates 10, 12. The detected output is supplied to a measuring circuit. |
