Samsung CLP 510N - Color Laser Printer, Service Manual

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5-13
Samsung Electronics
System Outline
Service Manual
5.2.5 Print
After sensing the ITB home position the following tasks are performed,
Send Psync signal to controller -> Operates virtual timer for each color(Vdata) -> Forms latent
image on OPC drum -> Supplies toner on OPC drum -> Transfers image to ITB (T1 ) -> Pickups a
paper -> Transfers image to a paper (T2)
1)Check ITB Home (Treated by Home interrupt): It is designed to detect ITB HOME every 3 seconds.
a) ITB Home sensing
b) If a test mode is set up, a test pattern is printed.
c) A counter value is set up that addresses the timing to turn on page sync.
d) The virtual timer for each color (Y, M, C, and K) is set up
e) If Home is not detected every 3 seconds, an error is reported.
2)Paper path and print
a) Printing paper from cassette, MPT and SCT is picked up
b) Control paper path
* Stop when the leading edge of a piece of paper reaches the feed sensor.
* If the leading edge doesn't reach the feed sensor, it is an error.
* While transferring the last color to the ITB, re-feed the paper.
* Checks if the paper reaches the exit sensor in certain time. If it reaches too soon, or it doesn't
reach, it is an error.
* Checks that the paper passes the exit sensor or not.
c) Jam check
* Check reaching time and passing time for the paper reaching and passing the feed and exit
sensors. If time exceeds a certain time, it is an error.
d) Duplex control
* After passing the exit sensor, the duplex clutch is operated to mechanically change the direction
of the paper flow in order to print the other side.
e) Printing sequence and motion for each color
* Use a virtual timer for printing the colors in sequence. (Yellow, Magenta, Cyan, Black)
> What is a Virtual Timer?
A virtual timer is a mathematical function for creating regular action at fixed time intervals. The stan-
dard setting is for a 5msc timer interrupt.
5.2.6 Post-Print
This is the last stage of the printing process. Its functions are described below.
a) Clean transfer rollers
b) Stop all virtual timers
c) Initialize parameters used in the printing process.
d) Stop motors