Rotation determination device

A rotation determination device comprising:

• an encoder connected to a rotating body and configured to generate two pulse signals that are out of phase with each other due to a rotation of the rotating body;
• a detector configured to detect a rising edge and a falling edge of the two pulse signals as a signal change;
• an acquisitor configured to acquire levels of the two pulse signals received from the encoder as input signal levels;
• a setter configured to set reference signal levels as the input signal levels, when power is initially supplied to the encoder;
• an edge pattern determiner configured to determine an edge pattern based on the detected signal change in one of the pulse signals and an unchanged input signal level (H level or L level) of the remaining pulse signal;
• a memory configured to store edge patterns corresponding to the reference signal levels in states where the two pulse signals match (“H, H”, “L, L”) and reference signal levels in states where the two pulse signals differ (“H, L”, “L, H”), and
• a rotation determiner that compares the edge pattern determined by the edge pattern determiner with the specific edge patterns stored in the memory, and that is configured to determine that the rotating body has been rotationally operated when the edge pattern determined by the edge pattern determiner matches the specific edge pattern.