Patent ID: 8164295

Claim:
A stepping motor controlling device comprising: a first clock signal generator that generates a reference clock signal that is a reference for operation timings of rotationally driving a plurality of stepping motors; a second clock signal generator that, on the basis of the reference clock signal, generates, for each of the plurality of stepping motors, speed control clock signals that determine respective rotational speeds of the stepping motors; a plurality of drivers that are provided respectively for the plurality of stepping motors, and that, on the basis of the speed control clock signals for the respective stepping motors, generate pulse excitation signals and input the pulse excitation signals to the stepping motors to rotationally drive the stepping motors; and a controller that controls the second clock signal generator to generate the speed control clock signals such that phases of the respective speed control clock signals for the plurality of stepping motors differ from one another, wherein the second clock signal generator comprises: a counting circuit to which the reference clock signal is inputted, and that counts a number of pulses of the reference clock signal; and a plurality of comparing circuits that are provided respectively for the plurality of stepping motors, and to which a count value from the counting circuit is inputted, and at which are set in advance count value range data expressing ranges of the count value, the comparing circuits comparing the inputted count value and the ranges of the count value, and generating pulses according to whether the inputted count value is within the range or outside of the range of the count value, and wherein the controller sets in advance, for the plurality of comparing circuits, count value range data expressing ranges of the count value that differ from one another at each of the plurality of comparing circuits.