| 摘要 |
To improve the tolerance of acoustic ink printers to changes in their free ink surface levels, provision is made for significantly reducing the effect of half wave resonances on the acoustic power density of the acoustic beam or beams that are incident on the free ink surface of such a printer, thereby reducing its focusing sensitivity. Some of the approaches that are taken to accomplish this rely upon acoustic losses to damp out the halfwave resonances and anti-resonances, while others employ multi-frequency rf voltage pulses for driving the droplet ejector or ejectors so that the acoustic power perturbations caused by the half wave resonances and anti-resonances of the different frequencies tend to neutralize each other. Indeed, the use of an acoustically lossy ink to dampen the half wave resonances and anti-resonances is compatible with selecting the frequency content of the acoustic radiation to neutralize them, so a combination of those two techniques can be employed, if desired, to carry out this invention.
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