Operating Principles; Engine Operation; Scanner Head Operation - Epson FilmScan 200 Service Manual

2.1 ENGINE OPERATION

This section describes the functions and operating principles of the FilmScan 200 engine.
The engine contains a CCD image sensor with a reading resolution of 1200 dpi. The engine consists
of two main sections: the scanner head and the carriage movement mechanism.

2.1.1 Scanner Head Operation

The scanner head on the optical unit is comprised of the CCD image sensor and the light source used to
enable reading. Figure 2-1 shows a cross section of the scanner head.
Lens
The light source is made up of three noble-gas fluorescent lamps - one green, one red, and one blue. To
read a color original image, the three primary colors (red, green, blue) must be read individually.
If the image is to be reproduced on a CRT, the individual readings are reconstituted on the display.
To read individual colors, the scanner illuminates the original film separately with each color of light. The
green lamp is the light source for reading the green component; the red lamp is for reading the red
component; and the blue lamp is for reading the blue component.
The operation of the CCD image sensor is divided into the three blocks show and described below.
Figure 2-2 shows the relationship between these three blocks. Light passed through original film strikes
the photosensitive section "1.", where photoelectric conversion takes place; a signal charge accumulates
that is proportional to the received light energy.
The transmission section "2." transmits the accumulated signal to the output section "3.". The output
section outputs the received signal charge in the form of an electrical signal.
Each of the three CCD sections is explained in greater detail below.
Rev. A
Inverter Board
CCD Image Sensor
Figure 2-1. Scanner Head Cross Section
Light
1. Photosensing Section
2. Transmission Section
3. Output Section
Signal Output
Figure 2-2. Image Sensor Mechanism Functions
G Lamp
R Lamp
B Lamp
Film
Optical Unit
Function
Photoelectric conversion and
signal charge accumlation
Signal charge transmission
Signal charge detection and
output

OPERATING PRINCIPLES

2-1