Electronic Systems; Astra 1220U Electronic Systems - UMAX Data Systems Astra 1220U Service Manual

2. Electronic Systems

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Astra 1220U Electronic Systems

The Astra 1220U consists of several electronic component systems which work together when a document
is scanned. The systems and their functions are described as follows (see Fig. 2-1 below).
A scanning lamp to illuminate the document.
An optical system that uses mirrors and lenses (the optical system) to focus the reflected light from the
surface of the document onto a Charged Coupled Device (CCD).
A mechanical system that uses a stepping motor attached to a gear assembly. The gear assembly drives
a timing belt to move the optical assembly (carriage) when scanning.
A photo-electrical conversion system, using a CCD which produces a string of analog electrical signals
representing a straight line image of a document.
An image processing system that converts the analog signals from the CCD into digital signals.
An interface board to connect the control signals of control circuit to image processing unit, the optical
system and transmission subsystem.
Host Computer
Astra 1220U Electronic Systems
The Opto-Mechanical System
The Photo-Electrical Converter
The Analog to Digital Converter
The Host Computer Interface
Function Blocks
Test Timing Diagrams
Connectors
CCD Pin Assignment
Control
Circuit
Image Processing
Circuit
Fig. 2-1: Scanner Systems
Object Glass
Optical
Lamp
Subsystem
Photo Sensor
Transmission
CCD
Subsystem
Service Manual
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