A3 Size Color Flat Bed Scanner GT-30000 Revision A
OPERATING PRINCIPLES Mechanical Operation of the Scanner 24
2.2 Mechanical Operation of the Scanner
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. Optical Unit Structure", 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.
The vertical distance between the lamp plus the mirror in the Lamp/mirror unit
and the document surface remain constant. The vertical distance between the
mirrors in the Mirror unit also remains constant. However, the horizontal
distances between the Lamp/mirror unit (rate = x2) and the Mirror unit (rate =
x1) as well as between the Mirror unit and Lens unit are constantly changing.
The stepping motor drives both movable units via wires.
The CCD sensor and the lens are united into one unit, which is semi-fixed on
the base frame.
The scanner is that the CCD lens focus is fixed.
Figure 2-2. Optical Unit Structure
Document
Variable
Glass
Lamp/mirror unit
Fixed
Variable
CCD sensor
Mirror unit
Lens unit
X1 X2
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