| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous operation at retention operation, and abnormal heating or damage of a motor or a motor driving element caused by abnormal operation at driving operation. SOLUTION: Protective circuits 11 and 12 are judged as driving operation from excitation current set values IS1 and IS2 held at carriage current setting registers 9 and 10 or detected currents IA and IB for indicating excitation currents at motors 15 and 18. Under these conditions, the protective circuits 11 and 12 are judged as abnormal operation when a phase change of phase signals PSA and PSB are not detected for a given time or above, and the phase signals PSA and PSB are stopped. In this case, the phase change can be detected by detecting directly an edge change of the phase signals PSA and PSB fed to a driving circuit. When the protective circuits 11 and 12 are judged as retention operation, the power is fed to driving circuits 14 and 17 directly without breaking the phase signals PSA and PSB. |
