| 摘要 |
PURPOSE:To detect the disconnection of a coil to be detected and a search coil by detecting the terminal voltage of the search coil, and comparing the ON and OFF of power supply to the coil to be detected. CONSTITUTION:In a 4-phase stepping motor 4, coils A, C are wound on a common bobbin 8, coils B, D are wound on a common bobbin 8', and composed to generate mutual induction therebetween. If the coil A is, for example, disconnected, the signal of terminal OS0 is altered from ''1'' to ''0'', a current i0 does not vary. Accordingly, a current i2 is not generated. Thus, the terminal voltage VC of a coil C does not drop, but remains at power source voltage EB. and the signal of the terminal IB2 remains ''1''. At this time the terminal voltage VA of the coil A alters from ''0'' to ''1'' at the signal of a terminal IB0 irrespective of the disconnection of the coil A due to the power source voltage EB given through a resistor 100 and a diode 90. Thus, when the coil A is disconnected, signals of ''1110'' is input to terminals IB0-IB3 to be discriminated as abnormal. |
