| 摘要 |
PURPOSE:To detect displacement of a movable part at a high speed stably with high accuracy by arranging a light emitting part at the central position in opposition to a swingable key top having a reflection mirror and providing plural light receiving parts around it. CONSTITUTION:When there is not displacement on the movable part K and the key top 3 is vertical with respect to an axis of a housing 1, laser light emitted in an axial direction from a micro-lens 6 through an optical fiber 7 is reflected in a reverse direction by the reflection mirror 4. As a result, the reflected light is not detected with any light receiving part 8 in this state and it is detected that the displacement is zero. On the other hand, when the movable part K is slightly displaced and the key top 3 is inclined by a small angle against the force of a spring 2, the laser light emitted in the axial direction is reflected with the angle twice as large as the inclined angle of the key top 3 by the reflection mirror 4. This reflected light is made incident on the light receiving part 8a and detected as an electrical signal through an optical fiber 10. Accordingly, the inclined angle of the key top 3 is calculated by the recognition of the light receiving part 8a and the quantity of displacement and the direction of the movable part K can be detected.
|
