Specifications

2.5 HVPSA

Figure 2–11 shows the high-voltage bias circuits that are used by the

xerographic processes discussed in Section 2.3. Not shown in Figure 2–11 is

the HVPSA/fuser interconnect that makes connection to the DC control board.

Figure 2–12 photographically shows the locations of the high-voltage terminals.

The HVPSA communicates with the DC control board through the serial

and signal lines. IC402 is a communication gate array that provides

two-channel serial interface to IC202 on the DC control board.

IC401 is a custom integrated circuit that provides the following:

• The ac bias coupled with dc bias used by the primary and development

processes. The dc component varies according to laser beam intensity

and to the setting of the user assessable density adjustment. The HVPSA

couples this dc component to the development bias.

• The transfer bias switches from negative for cleaning and to positive for

printing.

• The static eliminator removes the residual transfer charge from the paper

sheet.

• TB402 and the contact plate capacitor provide an ac ground path for the

transport entrance guide.

The HVPSA contact plate mechanically connects the HVPSA to the EP-ED

cartridge and contains the transfer roller and static eliminator. The coil

and ﬂat springs of the contact plate press against metal contact pads on the

HVPSA circuit boards. The spring holding pressure comes from the screws and

clips that are used to mount the HVPSA and contact plate.

2–22 Technical Description