| 摘要 |
<p>1399066 Ink-jet printers INTERNATIONAL BUSINESS MACHINES CORP 24 Oct 1973 [11 Dec 1972] 49511/73 Heading G4H An ink-jet printer incorporates logic 28, Fig. 5, for adjusting the phase relationship between drop-forming and drop charging signals in accordance with the sensed charge on a series of test drops. Test signals are derived from a clock 30, Fig. 6 (not shown), and are applied to a nozzle vibrator 12 and an electrode 14, the charge on the test drops being monitored by a sensor 16. Clock 30 comprises a ring counter which produces pulse-trains F1-F8, Fig. 2 (not shown), successively displaced by # of a period; pulse train F1 is used to drive vibrator 12. One of F1-F8 is used to control a gate 78 through which data signals pass from a generator 76 to the charging electrode 14: this pulse train is selected by gates 82 or 88 (A1-A8) during a print or a test phase respectively, the particular gate which is enabled being determined by the output of a modulo-8 counter 48 controlled by the output from sensor 16. In an initial test phase counter 48 is set to 0 and gate A1, 88 passes pulse train F1 as test charging pulses via gates 92, 42 to electrode 14, sensor 16 (which comprises a threshold device) determines whether or not the test drops have been fully enarged and sends an output to counter 48 which enables one of gates 94 or 44 so as to decrement or increment 48 (and thereby select a different pulse train). During the remainder of the initial test period the count in 48 is alternately stepped up and down by 1 according as the drops cease to be or become fully charged; at the end of this period gate 78 is enabled by the prevailing pulse train F. The possibility that the count in 48 may be wrong by a count of 1 does not matter in practice as the counter output is fed to decoders 80, 86 which select the gate A corresponding to a count of 3 less than the actual count (e.g. A2 for a count of 5) so as to produce a "broader" print phase charging pulse than is used in the test phase. Subsequent test phases, which may take place during a "carriage return" operation for example, are as above except that counter 48 is not initialized to 0.</p> |
