HP 4 C2001A, C2021A, 5n C3952A, 5 C3916A manual Duplex Printing, Switchback Assembly, Holding Tray

Duplex Printing

N o t e	The bold text and numbers in the following
	description refer to parts shown in Figure A-2.

When the printer is operating in duplex mode, the print images are printed in reverse order. Page two prints on the first pass of the paper through the printer and page one prints on the second pass through.

Switchback Assembly

To print the first pass, the paper goes through the printer paper path, where it is developed and fused. As the paper exits the fuser, the Switchback Solenoid (1) is activated. The Switchback Solenoid moves the Switchback Input Paper Guide (2), routing the paper into the Switchback mechanism. The Switchback Stepper Motor (3) then pulls the paper out of the printer into the Switchback Assembly. (The paper can be seen coming out of the top of the Switchback Assembly.)

As the paper moves through the Switchback Assembly, the spring loaded switchback Paper Reversing Guide (4) and its attached flag is moved, activating the Switchback Paper Sensor (5).

The paper continues to move out of the Switchback Assembly until it passes the switchback Paper Reversing Guide. The switchback Paper Reversing Guide returns to its original position when the paper passes it. The flag attached to the guide switches the electrical state of the switchback paper sensor. This signals the Duplex Control PCA (6) that the paper has advanced far enough to reverse direction. The Duplex Control PCA then reverses the direction of the Switchback Stepper Motor, causing the paper to reverse direction and move into the duplex Holding Tray (7).

Holding Tray

The Holding Tray, as the name implies, holds the paper which has been printed on one side while the print engine prepares to print the second side. The major components of the Holding Tray are the Holding Tray Input Stepper Motor (8), the Holding Tray Output Stepper Motor (9), and the Holding Tray Paper Detect Sensor (10).

Duplexer A -3