(1) Field of the Invention
The present invention relates to a method of driving the 5-phase stepping motor.
(2) Description of the Prior Art
For driving the 5-phase stepping motor, the so-called standard, pentagon, and star drive methods have been proposed and employed in practice. However, when depending on the pentagon and the star drive methods, a half-step drive with 4-5-phase excitation is difficult to perform and, therefore, the standard drive method is chiefly employed for said half-step drive.
FIG. 1 is a circuit diagram for the standard drive method as the prior art.
In the drawing, the reference numerals 1 through 5 indicate phases A through E, respectively, each consisting of a coil wound around a stator pole of the 5-phase stepping motor. Each phase is actuated by transistors 6a through 6d to be in in-phase or antiphase with respect to the other phase. The numeral 7 indicates a power source for supplying field current to each phase.
As apparent from the drawing, in this drive method, four transistors are used for each phase and accordingly twenty transistors in total are required for composing an output step, which results in such drawback as increase in heat generation in the output step, enlarged size of the step, and complicated control circuit for controlling the step.
Further, because of a structure in which all phases are excited in parallel, the power source is required to supply four to five times as much as the rated current (current that can be supplied to each phase) of the motor correspondingly to 4-5-phase excitation. Thus, the conventional drive method has a disadvantage which requires the use of a power source of large current capacity.