| 摘要 |
An electronic system, which serves as a recorder (500) and an automatic player (300), is installed in an automatic player piano (100), and hammer sensors (26), which are implemented by photo couplers, report current hammer positions through analog signals (Vh) to a data processor (27) so that the data processor (27) analyzes pieces of hammer data for recording the performance in a set of music codes; the analog signals (Vh) are amplified through an operational amplifier (24a) and, thereafter, converted to discrete values (AD) of digital hammer signals so that an offset voltage is unavoidably introduced into the analog signals; when the photo couplers vary the light-to-photocurrent converting characteristics due to the aged deterioration, the data processor (27) takes the offset voltage into account, and calibrates the hammer sensors (26), thereby making the digital hammer signals correctly express the current hammer positions. |
