Printing System Models - Control of Color Imaging Systems: Analysis and Design - page 573

V bias

Dispenser

V dev

Trim
blade

PR

Mixing
auger

Magnetic
roll

Donor
roll

DMA

Waste

FIGURE 10.18 Example of a hybrid two-component development process.

Figure 10.18 shows an example of the two-component development system hard-
ware. The charge-to-mass ratio, Q = M, also called of the toner particles,

is one of the fundamental parameters in any EP printer. The blackness of the
image depends heavily on the magnitude of the tribo. The ratio between the number
of toner particles to the number of carrier particles in the developer mixture, called
the toner concentration (TC), is also an important parameter that changes over time
(unless ef

the tribo

'' ''

ciently controlled) due to a continuous toner development in high-speed
printers. In solid area development, the developed mass per unit area (DMA) on the
photoconductor depends on the development voltage V dev , physical and electrical
parameters of the development system, and the toner.
For a two-component conductive magnetic brush development system, several
quantitative theories have been developed that are available in the published litera-
ture. A simple theory is based on the assumption that the toner charge per unit area
completely neutralizes the photoconductor charge per unit area [13]. According to
this theory, the DMA (M = A, measured in mg cm 2 ) can be predicted by the following =

expression (see Problem 10.5):

M
A ¼

V dev e 0
( Q = M ) d p = K p

D ¼ ( 10 : 30 )

where
d p is the thickness of the photoconductor
K p is the dielectric constant of the photoconductor
e 0 is the dielectric permittivity of air
Q = M is the toner tribo (charge-to-mass ratio)