Toner Concentration Control (Pcdc); Toner Concentration Control (Adc) - Epson AcuLaser C8500 Service Manual

EPSON AcuLaser C8500

2.7.6.2 Toner Concentration Control (PCDC)

Concentration of toner in the developer (amount of toner to developer) is
reduced by printing. A certain amount of toner must be maintained in the
developer in order to obtain consistent printing quality. PCDS (Pixel Count
Dispense Control) calculates the amount of toner consumed by the developing
process by counting the video signals input to the ROS ASSY.
Turn on DISPENSE CLUTCH ASSY for the amount of time needed to supply
that amount of toner (dispense time), turning the Auger in the Developer Assy
to supply toner from the Toner Cartridge to the Developer Assy.
The method of counting video signals for PCDC entails charging and
discharging the capacitor corresponding to the video signal by CR circuit
arranged parallel to the video signal line.
Figure 2-55. Toner Concentration Control (PCDC)
Operating Principles
T

2.7.6.3 Toner Concentration Control (ADC)

In order to conduct consistent printing, the actual amount of toner in developer
must be detected while not being affected by laser radiation, and must be
maintained. With ADC (Automatic Density Control), BIAS development bands
are formed on the drum of the various colors (Y, M, C , Bk) by BCR voltage and
developing voltage of differing specifications when printing, and the
concentration of the bands is measured by ADC Sensor.
The measurement values are compared with reference values, and if the
amount of toner has decreased (if concentration of toner in the developer is
low), turn on the DISPENSE CLUTCH ASSY for the corresponding amount of
time (dispense time), turning the Auger in the Developer Assy by the drive from
DISPENSE CLUTCH ASSY, and thereby supplying toner from the Toner
Cartridge to the Developer Assy. If the amount of toner is excessive
(concentration of toner in the developer is high), the toner in the developer is
consumed by forming BIAS development bands the number of times it takes
for the toner to be reduced to the proper amount.
Figure 2-56. Toner Concentration Control(ADC)
Revision C
2-54