Epson GT-1200, Руководство по обслуживанию

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GT-12000 Operating Principles
Rev. A
2-2
2.2 MECHANISM OPERATING PRINCIPLES
Compared with other EPSON scanners, the main feature of this scanner
lies in its new optical mechanism used for reading images. Instead of the
united lamp & CCD movement system used for other scanners, this
scanner scans with the fixed CCD sensor and separate lamp and the
mirror units. Since the color CCD line sensor is used for the reading
device, only one light source is equipped and light is separated through
the RGB color filter.
As shown in Figure 2-2, the light source (high luminance cold cathode
xenon lamp), the first reflection mirror unit and the second reflection mirror
unit move independently at their own speed. Therefore the length of the
incident light reflected from the document to the CCD sensor is kept
constant. (Otherwise, excluding the fixed L1 and L2, LV1 and LV2 keep
changing to make the incident light length “L” constant.) Drive from the
stepping motor moves each mirror unit via the wires.
The CCD sensor and the lens are united into one unit, which is semi-fixed
on the base frame. For focusing function, it moves toward the optic with
the drive sent from the motor. (The focusing area with this function is from
0 to 5 mm (maximum) above from the glass surface.
x1 x2
L1
(Fixed)
Document
LV1 (Variable)
Document
Glass
L2
(Fixed)
Mirror Unit
Lamp/Mirror unit
Lens Unit
CCD Sensor
LV2 (Variable)
Figure 2-2. Optical Unit Structure