Epson ES-1200C Pro PC, Service Manual

Page: 37 / 95

Service Manual
Operating
2.1 ENGINE OPERATIONS
This section describes the functions and operating principles of the engine. The
engine contains a image sensor with a reading resolution of dpi. The engine consists of
two main sections: the sensor head and the carriage-movement mechanism.
2.1.1 Scanner-Head Operations
The scanner head (carnage assembly) is comprised of the image sensor and the light source
used to enable reading.
2-1 shows a cross-section of the scanner head.
n
Image Scanner
Figure 2-1. Cross-Section of the Scanner Head
The light source is made up of four noble-gas fluorescent lamps — two green, one red, and one
blue.
To read a color original, 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 document 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; the blue lamp is for reading the blue component. The operation of the
image sensor is divided into the three blocks shown and described below.
Light
1. Photosensitive Section
2. Transmission Section
3.
Output Section
Signal Output
Function
Photoelectric conversion and
accumulation
Signal-charge transmission
Signal-charge detection and
output
Figure 2-2. Functions of Image Sensor Mechanism
Figure 2-2 shows the relationship between these three blocks. Light reflected from
document strikes the photosensitive section where photoelectric conversion takes place; a
signal charge accumulates that is proportional to the received light The transmission
section transmits the accumulated signal to the output section The output section outputs
the received signal charge in the form of an electrical signal.
Rev.
2-1