| 摘要 |
PURPOSE:To make the structure rigid, to make the price low and to ensure the stable display, by differentially amplifying the outputs of two light receiving elements, which receive the light that has been emitted from the first (second) light emitting element and has passed the first (second) optical-amount varying part, by an electronic circuit. CONSTITUTION:A fixed light polarizing plate 1 comprises light polarizing plates 1a and 1b on concentric circles and the plate 1 is fixed to a container 10. A rotary disk 2 comprises light polarizing plates 2a and 2b and a slit machined plate 11. The disk 2 is attached to a supporting shaft 3 so that the disk can be rotated. When the amount of light passing the light polarizing plates 1a and 2a is minimum (maximum), the amount of light passing the light polarizing plates 1b and 2b becomes maximum (minimum). The rotary disk 2 is rotated in correspondence with the change in angle of a structural body. The amounts of the light beams from light emitting elements 4a and 4b are changed by the light polarizing plates 1a-2b, and the outputs of light receiving elements 5a and 5b are changed. The data of the rotary angle is sent to a differential amplifier. Thus the structure is made rigid, the price is made low, errors are made few and the stable display can be ensured. |
