Patent ID: 7532141

Claim:
A pulse width modulation method, which modulates a digital signal and generates a pulse width modulation signal in a pulse width modulator, by using a digital signal output unit which receives an input signal on a cycle basis and outputs the digital signal corresponding to the input signal and the pulse width modulator which is capable of modulating the digital signal, the value of which is included in a prescribed value range in synchronization with the cycle, the pulse width modulation method comprising: outputting to the pulse width modulator a first value corresponding to the input signal as a first digital signal at a first timing by the digital signal output unit; determining a limited value range based on the first value by the digital signal output unit; determining a second value corresponding to a new input signal by the digital signal output unit; judging whether or not the second value is included in the limited value range, and when the second value being judged to be included, outputting the second value to the pulse width modulator as a second digital signal, and when the second value being judged not to be included, outputting a value included in the limited value range to the pulse width modulator as the second digital signal at the second timing at which at least one cycle has elapsed from the first timing by the digital signal output unit; and modulating the pulse width of the second digital signal and generating the pulse width modulation signal, by the pulse width modulator.