Epson 1250 - Perfection Photo Flatbed Scanner, Service Manual

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EPSON Perfection 1250/1250 PHOTO Technical Overview
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2.1.2 Carriage Mechanism
To generate an image, the document is scanned in the main scanning direction
(single line scan) by the CCD sensor, and then in the sub-scanning direction
(multiple line scan) by the carriage assembly as shown in Figure 2-3.
The color CCD sensor can only scan a single line in the main scanning
direction (which runs parallel to the carriage assembly direction). In order to
scan the second and subsequent lines in the sub-scanning direction, the CCD
sensor is moved by the carriage unit. Scanned data is then sent to the control
circuit board. When line
n
is being scanned, the image data for line
n-1
is
processed at the same time, so that scanning is continuously carried out.
Figure 2-3. Carriage Movement
The carriage assembly slides along the guide rail in the sub-scanning direction.
This movement is powered by the CR motor via the drive pulley to the timing
belt which is secured to the carriage unit. The scanning starting position is
determined by the CR HP sensor, which is located on the control circuit board.
Figure 2-4. Carriage Operation
1 pixel
Sub-scanning direction
(from carriage movement)
Main scanning
direction
Document
2nd line 1st line
Scanner head
(carriage)
Front
Carriage Assembly
CR HP sensor
Rear
CR Motor
Timing belt
Driven Pulley
Drive Pulley