The machine checks the ITB home position to ensure the correct image write start position using the ITB home position sensor (PS71), which checks the position

with reference to the home position detection faces (4 light-blocking faces) found on the edge of the ITB belt as follows:

1) When it receives the print command, the DCNT Board starts to rotate the ITB belt. When PS71 detects a light-blocking face, it sends TOPSNS to the DCNT

Board.

2) The DCNT Board assumes the first TOPSNS signal to indicate the home position (HP1), and increases the count each time a new light-blocking face is detected

(HP2, HP3, HP4).

3) In the case of full color operation, the DCNT Board uses these signals to generate the vertical sync signal (/TOP) 4 times, and sends them to the SCNT Board.

Thereafter, the DCNT Board receives video data of each color from the SCNT Board 4 times, and draws images of individual colors on specific points on the ITB.

The DCNT Board monitors the TOPSNS signal at all times, and will identify a fault in the ITB home position sensor in the event of the following condition; as a

result, it will stop the printer engine and, at the same time, will communicate the nature of the fault to the SCNT Board.

2-24

DCNT Board

Memory tag contact

Memory tag

Drum cartridge

F-2-38

0008-1713

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