Abstract of
JP9331698
PROBLEM TO BE SOLVED: To improve the positional accuracy of a stepping motor, by deciding through a sensing circuit whether the currents flowing in motor coils are increasing or decreasing in specified terms, and by changing over into each other through controlling circuits output switching elements subjected to ON-OFF by timing signals in the respective specified terms. SOLUTION: Providing a sensing circuit 108 for the increases or decreases of output currents, current control signals S1, S5 of first and second phase sides are inputted respectively to it to decide whether the currents flowing in motor coils L1, L2 of the first and second phases are increasing or decreasing in specified terms. During the first and second phase motor coil currents at terminals OUT1-OUT4 are increasing, the circuit 108 outputs control signals S4, S8 respectively to circuits 102, 105 for controlling output switching elements. The signals S1, S5 control digitally by the two values of H and L the current directions of the motor coils L1, L2. When the signal S1 is H, turning on switching elements 11, 12 and turning off switching elements 13, 14, the terminals OUT1 and OUT2 are connected respectively with a power supply VDD and a chassis ground. When the signal S5 is L, the connections of the terminals are reversed. Operating the second phase similarly too, the vibration of a stepping motor is removed to improve its positional accuracy.
