Toner Density Control Circuit - Printronix L5020 Maintenance Manual

Toner Density Control Circuit

The toner density is controlled by the output voltage of the toner density sensor.
When the toner density in the vicinity of the toner density sensor drops below 11%,
the output signal (TDSO) from the toner density sensor goes low, the toner supply
roller drive signal (TSMO) is output from the gate array, and the toner supply clutch is
engaged for 1 second.
This toner supply action can also be executed by an engine action request command
from the controller. When the printer is offline, if the controller issues a command to
supply toner, then the gate array asserts the toner supply clutch drive signal, causing
the toner supply clutch to engage for 1 second.
Further, the monitoring cycle of toner density by the toner density sensor can be set
as a dot count (a LED illumination dot number, from 1 through 254 from density
detection to next density detection) by the developer toner density monitoring cycle
setting command from the controller. (However, if the dot count value does not reach
the set value after 9 seconds, monitoring begins at 9 second intervals.)
3–42 Electrical System and Adjustments