GB1346619A - - Google Patents

Abstract

1346619 Facsimile apparatus A B DICK CO 4 May 1971 [8 May 1970] 13001/71 Heading H4F [Also in Division G4] In an ink drop writing system in which selected ink drops of an ink drop stream are charged in accordance with information signals and deflected electrostatically in accordance with their charges on to a recording medium, wherein the magnitude of the charge applied to a subsequent drop in the ink drop stream is modified to compensate for the effect on the charging of the subsequent drop of the electrostatic field of the preceding charged drop. Alpha-numeric, digital, facsimile or oscillographic information may be recorded. The charge modification means, which increases the charge to a subsequent drop to compensate for the effect of the charge on the just formed (i.e. preceding) drop, is inhibited when the subsequent drop has no information signal for charging associated therewith, and is also inhibited when the preceding drop has no information signal for charging associated therewith. The change modification means may comprise a variable gain amplifier having a feedback network which is enabled to effect the required compensation (Fig. 4, not shown). For more accurate printing the degree of compensation is varied non-linearly in accordance with the amplitude of the charge which is applied to a drop, the video information specifically being in digital form and converted into analogue form non-linearly or linearly in dependance upon whether or not respectively charge compensation is being effected (Fig. 5, not shown). Compensation may be applied for only certain levels of charge (Fig. 6, not shown).