| 摘要 |
PURPOSE:To enable increase in accuracy over a wide range by disposing a light emitting element and photodetector in such a way that the light emitted from said element passes through the fixed 1st polarizing filter and the 2nd polarizing filter which is freely turnably attached. CONSTITUTION:When turning torque is applied to a fulcrum shaft 3, a polrizing filter 6 turns as well but a filter 5 is fixed and therefore the angle between the absorption axes of the two polarizing filters changes according to the turning amt. of the shaft 3. The transmittance of the light from a light emitting diode 1 to a phototransistor 2 passing through the two polarizing filters is max. when the angle between the absorption axes of the respective polarizing filters is zero and said transmittance is min. when said angle is 90 deg.. The transmittance is smaller as the angle between the two absorption axes is larger at the intermediate thereof. |
