Service Manual
2. Electronic Systems
What’s in this Chapter:
•
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
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.
Object Glass
Lamp
Image Processing
Circuit
Optical
Subsystem
Photo Sensor
CCD
Control
Circuit
Host Computer
Transmission
Subsystem
Fig. 2-1: Scanner Systems
3
Summary of Contents for Astra 1220U
Page 1: ...Astra 1220U Color Scanner Service Manual UMAX Data Systems Inc 0898 e...
Page 4: ...Pin Assignment 44 iv...
Page 14: ...Service Manual AD Pin Assignment 10...
Page 15: ...Service Manual Motor and To CCD Board Pin Assignment 11...
Page 16: ...Service Manual Power Code Pin Assignment 12...
Page 17: ...Service Manual EPP to USB Bridge Pin Assignment 13...
Page 19: ...Service Manual 3797P 15...
Page 37: ...Service Manual Appendix B Scanner Outline Diagram 312 83 98 471 33...