Xerox 3300MFP Service Manual - Page 58

Theory of Operation Safety Features ■ To prevent overheating ■ 1st protection device: H/W cuts off when detecting an overheating ■ 2st protection device: S/W cuts off when detecting overheating ■ 3st protection device: Thermostat cuts off power to the lamp ■ Safety device ■ Fuser power is cut-off when the front cover is open ■ LSU power is cut off when the front cover is open ■ The temperature of the fuser cover's surface is maintained at less than 80ºC to protect the user and a caution label is attached where the customer can see it easily when the rear cover assembly is opened. LSU (Laser Scanner Unit) Resolution Spot Size Laser Property fθ Property 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 principle of the polygon mirror to create a 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 /HSYNC signal and sends it to the engine when the laser beam of the LSU reaches the end of the polygon mirror, and the engine detects the / HSYNC signal to arrange the vertical line of the image on the paper. After detecting the /HSYNC signal, the image data is sent to the LSU to arrange the its margin on the paper. Each facet of the polygon mirror scans a single line. Item Main Sub Variation Wavelength Power Specification Real 600 dpi 75 + 20/-20 µm 85 + 25/-25 µm 40 µm/50 µm 785 + 10/-15 nm 0.33 mW ± 0.02 mW Vignetting Min 80% Magnification error Max 0.7% Partial Magnification error max 1.5% Item main direction x sub direction -beam diameter at the level of 1/e2 of intensity -at the spot location of 0, ±100 mm of image height main/sub, within image height of 100 ~ +100 mm range at 25 °C at the center of image on the focal plane, with stationary condition, power supplied at DC 5 volt spot power variation within image height of -100 ~ +100 mm based on the printable area, 216 mm based on the 2.54 mm width within the printable area, 216 mm 2-16 Phaser 3300MFP Service Manual