| 摘要 |
<p>An automatic player piano is equipped with a position detecting device (90,100) for detecting current positions of the black/ white keys, and the position detecting device (90,100) radiates light beams across the trajectories of the black/ white keys, wherein the position detecting device (90,100) stores a variable relation between a relative value of the amount of light and the current positions for determining the current positions so that the position detecting device (90,100) keeps the reliability of the current positions against aged deterioration.</p> |
