Panasonic KX-P7100 manual Laser Scan Unit Exposure, Operation Theory, Laser Beam

KX-P7100

1.9.Laser Scan Unit ( Exposure )

1.9.1.Operation Theory

The light beam from the laser diode ( light source ) is modulated by the digital signal (nVIDEO) and converted to parallel light waves by the collimator lens. The beam is then sent to the rotating polygon mirror (polygon scanner), where it is reflectedthrough the lens and then focused onto the OPC drum surface. The diameter of the beam is about 80 µm, and the light moves across the surface of the OPC drum in the scanning directionof right to left. As the drum rotates ( sub-scans ), a static image is formed where the laser beam touches the drum surface.

The laser beam is also deflected to the timing sensor. This sensor controls the start timing of scanning on the drum, providing a consistent left margin. The CPU uses the timing sensor to detect abnormal signals.

1.9.2.Laser Beam

The laser beam is pulsed on and off by the digital signal (nVIDEO) to form a latent image of two different voltage potentials on the drum, as shown below.

Laser Diode Specification

Item	Minimum	Standard	Maximum
Oscillation Wavelength	770	785	800	nm
Output Light Power	0.315	0.350	0.385	mW
(OPC Drum Surface)

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