the discharger bias switch signal (/DCHGUP) turns “H” the low output bias changes to “L” and
the circuit applies a high voltage output bias. The high voltage output bias is applied only at
the trailing edge of a single side print and during the second side of a duplex print.
e. Toner sensing/cartridge sensing
The EP-72 cartridge has a toner sensor.
The DC controller detects the toner level and whether a cartridge is installed when the devel-
oping AC bias is applied to the developing cylinder by the DEVELOPING AC BIAS DRIVE signal
by checking the TONER LEVEL signal (TONSNS) voltage.
2 - 18
CHAPTER 2