Engine control system (engine control unit and power assembly)
The engine control system coordinates all print engine activities. The engine control system includes
both the engine control unit (ECU) PCA and the engine power-assembly-PCA.
NOTE In other HP LaserJet products, the ECU and power functions are combined onto one
PCA known as the controller PCA or the dc controller PCA. In the HP LaserJet 1022 series
printers, the control functions are primarily relegated to the ECU PCA and the power functions
to the engine-power-assembly PCA.
The ECU controls the following systems and functions:
■ Printer-engine control
■ Paper-motion monitoring and control (printing)
■ Motor
■ Printer laser/scanner unit
The engine power assembly provides the following features in the power system:
■ AC power distribution
■ DC power distribution
■ Overcurrent/overvoltage protection
■ High-voltage power distribution
Printer-engine-control system
Paper motion monitoring and control
The ECU controls paper motion in the printer by continuously monitoring the two paper sensors and
coordinating the timing with the other print processes.
For a detailed explanation of paper movement and the interaction of the sensors and pickup solenoid
with the paper-movement process, see
Printer-paper feed system on page 51.
Motor
The ECU controls the motor. The motor drives all of the paper movement in the printer.
46 Chapter 4 Operational overview ENWW
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