| 摘要 |
The application of the voltage on a charge electrode to selectively charge droplets of a pressurized conductive ink stream is synchronized with the break off of the droplets from the stream so that the break off occurs in the third quarter of the time period during which the charge voltage is placed on the charge electrode. To determine in which quarter that break off is occurring, the charge voltage is placed on the charge electrode at the same time for two adjacent quarters of a cycle during each of the two adjacent cycles in which a disturbance is placed on the stream by drive means such as a transducer, for example, to produce two droplets. During the next application of the charge voltage on the charge electrode, the charge voltage is applied for the last of the prior two adjacent quarters and the next adjacent quarter during two adjacent droplet producing cycles. During the third application of the charge voltage on a charge electrode, the voltage is placed on the charge electrode for the last of the prior two adjacent quarters of the second application and the next adjacent quarter during each of two adjacent droplet producing cycles. The final periodic application results in the charge being placed on the charge electrode during the last of the prior two adjacent quarters of the third application and the next adjacent quarter during each of two adjacent droplet producing cycles. When the charge voltage is applied to the charge electrode at the time of break off, an optical sensor, which is disposed a predetermined distance downstream from the charge electrode, senses a gap between the two charged droplets because they will have repelled each other. This enables determination of the location of the break-off point of the stream with respect to when the charge voltage is placed on the charge electrode so that there can be synchronization between when the charge voltage is applied to the charge electrode and the break-off point of the droplets from the stream.
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