Samsung ML-1755 Service Manual page 18

4.2.4.5 Safety Relevant Facts
• Protecting device when overheating
- 1st protecting device: H/W cuts off when detecting an overheating
- 2nd protecting device: S/W cuts off when detecting an overheating
- 3rd protecting device: Thermostat cuts off the power
• Safety device
- The power of the fuser is cut off when the front cover is open.
- The overheating safety device for customer
- Maintains the surface temperature of the Fuser Cover under 80°C and attach the caution label
inside of the rear cover where customer can find easily.
4.2.5 LSU (Laser Scanner Unit)
The LSU unit is controlled by the video controller. It scans the video data received from video controller
with laser beam by using the rotation principal of the polygon mirror to create the latent image on the OPC
drum. It is the core part of LBP.
The OPC drum rotates as the same speed as the paper feeding speed. It creates the /HS YNC signal and
sends it to the engine when the laser bean of the LSU reaches the end of the polygon mirror, and the
engine detects the /HS YNC signal to arrange the vertical line of the image on the paper. After detecting
the /HS YNC signal, the image data is sent to the LSU to arrange the its left margin on the paper.
The one side of the polygon mirror is one line for scanning.
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