Service manual

EPSON Perfection 1240U Revision A
Operating Principles Engine Mechanism 19
2.1.2 Carriage Move Mechanism
Scanning image is performed in the main scan direction (=1 line) by the CCD
sensor and in the sub-scan direction (=several lines) combined with carriage
unit movement. (See the figure below)
Line type, color CCD sensor can scan 1 line in main scan direction (parallel to
the carriage unit) by one time. When scanning next lines after the second line
in sub-scan direction, CR driving moves the carriage unit, which has CCD
sensor inside, and scan the other lines. The scanned data is sent to the control
board. The scanned data for “n” lines and “n-1” line are processed
consecutively.
Figure 2-3. Carriage Movement
Carriage Unit slides into sub-scan direction along with the guide rail. For this
sliding operation, the carriage motor drives the timing belt attached to the
carriage unit by conveying the driving force through the drive pulley and
reduction gear. Scanning start position is determined by CR HP sensor, which
is located on the control board. Since the stepping motor is used for CR motor,
carriage home position is controlled under the open loop system. (See the
figure below)
Figure 2-4. Carriage Operation
1 pixel
Document
Main Scan
Direction
Sub-scan Direction by
CR Movement
Second
Line
First Line
Scanner Head
(Carriage)
Rear
Front
Carriage Unit
CR HP Sensor
Driven Pulley
Drive Pulley
Transmission
Gear
CR Motor
Timing Belt