| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a liquid injection device reducing the stages of a smoothing filter and reducing switching loss, when carrying out power amplification using a digital power amplifier. Ž<P>SOLUTION: A drive wave signal WCOM is pulse modulated in a modulation circuit 26. The modulated signal is power amplified in a digital power amplifying circuit 28. The power-amplified modulated signal, for which power amplification is carried out, is smoothed at a smoothing filter 29 and outputted to a nozzle actuator in a liquid injection head 2. The digital power amplifying circuit 28 includes two steps of digital power amplifiers 27a and 27b having a push-pull connected switching device pair. The second digital power amplifier 27b is biased with the output of the first digital power amplifier 27a. While the number of steps for attainment voltage potential of the power-amplified modulated signal is made into a signal of multiple values, a supply potential VHV is adopted as an intermediate potential of a driving signal. That is, the supply potential VHV is adopted as a voltage maintenance voltage potential. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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