| 摘要 |
PURPOSE:To save labor in test printing and avoid wasting ink or paper by operating a signal-generating means, driving a piezoelectric element by an ink detection driving means, and comparing a detected waveform of a voltage between terminals of the piezoelectric element with a waveform to be outputted when a nozzle is preliminarily filled with the ink. CONSTITUTION:An oscillator 10 is operated by a signal from a CPU 1 to input an ink-detecting signal S1 to a piezoelectric element-driving circuit 7, which applies an exciting voltage on a piezoelectric element 9 according to the signal S1. The oscillator 10 sweeps the ink-detecting signal at a specified frequency of 200 to 400 kHz, whereby the piezoelectric element 9 is expanded and contracted at a speed according to the frequency, and a nozzle 17 is also expanded and contracted. A waveform at a resonant frequency when the nozzle 17 is filled with an ink I is preliminarily set in a RAM 12a in the CPU 1, and is compared with the present waveform by the CPU 1. When both data coincide with each other, a switch 6 is changed over to a timing-correcting circuit 5 to obtain a condition ready for printing. When both data discord with each other, the switch 6 is maintained in the present connection condition. |
