The transfer corona current output is turned ON and OFF by the high-voltage DCremote signal (DCON). Further, the output level of the transfer current is controlled bythe transfer charging level control signal (HVTTC).When the HVTTC signal is about 3 V or more and less than 11 V, the output of thetransfer corona current turns ON; it turns OFF when the signal is about 12 V or more.a. Transfer Corona Current OFFHVTTC is about 12 V.DCON is ‘0’.The comparator circuit turns OFF.The variable width pulse oscillator circuit turns OFF.The drive circuit turns OFF.The primary high-voltage transformer turns OFF.b. Transfer Corona Current Output ONHVTTC is less than about 11 V.DCON is ‘1’.The comparator circuit turns ON.The variable width pulse oscillator circuit turns ON.The drive circuit turns ON.The primary high-voltage transformer turns ON.In this condition, the high-voltage transformer sends high voltage that suits the outputof the transfer charging level control signal (HVTTC) to the transfer charging assembly.If an excess corona current flows from the transfer charging assembly because ofchanges in the environment, the return signal to the comparator circuit increases, andthe output decreases, causing the corona current from the transfer charging assemblyto decrease, thereby controlling the current to a specific level at all times.COPYRIGHT © 1997 CANON INC. CANON NP6045 REV. 1 MAR. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)CHAPTER 4 IMAGE FORMATION SYSTEM4-12
