Ricoh SP 8400DN Field Service Manual page 1406

7.Detailed Descriptions
Waste Toner
A: Silicone Pipe
B: Waste Toner Transfer Coil
The waste toner transfer coil transfers waste toner from the PCU to the waste toner bottle via a silicone pipe. The
silicone pipe is part of the main machine.
Toner Discarding
Overview
Printing with low toner coverage leaves a lot of uncharged toner in the development unit. This degrades developer
more quickly. To keep toner in the development unit fresh, the machine makes a belt pattern on the drum at the
end of a job when image coverage is less than 3%, to make sure that the equivalent toner for 3% coverage is
consumed. This supplies a certain amount of fresh toner to the development unit. The belt pattern is cleaned off
the drum, and the waste toner is stored in the cleaning unit and from there it goes to the waste toner bottle.
For these examples, let us say that toner consumption at 3% is 10 mg/m.
6% Coverage (Toner consumption ratio = 20 mg/m)
In the first example, we have 6% coverage. 20 mg/m of toner is sent from the development unit to the drum. 17
mg/m ends up on the paper and 3 mg/m is cleaned off the drum and goes to the waste toner bottle. 3 mg/m = 20
mg/m x 0.15. This factor of 0.15 is a constant for this development mechanism. In other words, at all times, 15%
of the toner applied to the drum does not get on the paper, and is discarded.
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C: PCDU
D: Waste Toner Bottle