Elektrographischer Schreiber

1,185,566. Recording systems. VARIAN ASSOCIATES. 8 Aug., 1968 [21 Aug., 1967], No. 37979/68. Heading G4H. In a recording system in which one of an array of writing electrodes 12 (Fig. 1) positioned over a recording medium 13 is selected in accordance with the value of an analog input signal Ei, digitized in an analog/digital converter 1, the converter 1 includes a dual comparator 21 in which the difference signal Ei of a current Ii representing the input signal Ei and a feedback reference current Ir representing the state of a binary coded decimal counter 7 is compared with two reference levels to determine whether the counter should count up, count down or stop counting. The reference levels are preferably Œ75 millivolts, the count being stopped when the error signal lies between these units. The outputs of the counter are fed to a decoder 11 which controls, via transistor gates 15, the electrodes to cause a charge image to be deposited upon the dielectric surface of paper 13, the image being developed by drawing the paper 13 against an inking slot 32.