Chapter 66-76.6.2 Developing Bias Control 0017-4353A DC bias and an AC bias are applied to the developing cylinder.The ASIC on the DC controller PCB outputs the developing AC bias drive signal (/DVACFOT), developing AC bias ON/OFF signal (/DVACON), developing DCbias drive signal (/DVDCFOT), and developing DC bias output level signal (/DVDCPWM) to apply the voltage generated by superimposing the developing ACbias over the developing DC bias to the developing cylinder.To prevent fogging of the drum, a DC bias higher than usual applied except during image formation and when the developing AC bias is applied for warm-uprotation.The developing DC bias is detected by the developing DC bias detection circuit, and is fed back to the DC generation circuit via the comparison circuit, thus con-trolling the DC bias voltage. The developing DC bias voltage changes with the primary DC bias voltage according to the image density information sent from theimage processor PCB.The remaining toner level is detected during warm-up rotation and when the developing AC bias is applied for printing. The remaining toner level detection signal(TNRCHKT) sampled from the antenna (for remaining toner level check) in the developing assembly is compared with the reference signal (TNRCHKD) receivedfrom the developing bias detection circuit.F-6-106.7 Toner Container6.7.1 Outline 0017-4354The structure of the toner bottle is shown below.The toner bottle is charged with 1-component, insulating, magnetic toner. The stirring rod in the toner bottle is rotated by the mina motor to supply toner into thedeveloping assembly through the toner supply port.F-6-11[1] Stirring rod[2] Toner bottle lever[3] Toner supply portJP7/JP8JP1/JP2TNRCHKTTNRCHKD/DVACFOT/DVDCPWM/DVDCFOTTo developingcylinderFrom remainingtoner level sensorDeveloping bias circuitASICCPUDeveloping DC biasvoltage detection circuitDeveloping AC biascurrent detection circuitRemaining toner leveldetection circuitDC generation circuitAC generation circuitComparisoncircuit/DVACONSuperimpositionHigh-voltage power supply PCBDC controllerPCB[1][3][2]
