Xerox Phaser 6128MFP Service Manual page 113

Phaser 6128MFP Service Manual
Control Circuit
The control circuit executes scanning of image data by controlling the image
scanner. A line of CCDs scans the original image one line at a time. When scanning
of one horizontal line is completed, the next line below is scanned. As this
continues, the original is scanned from end to end one line at a time and converted
to digital data as black-and-white information.
Because this image data is a set of digital signals, it cannot be transmitted using
an analog telephone line; it must be subjected to DA conversion (modulation). On
the other hand, the receiving Fax machine must perform AD conversion to restore
the incoming digital data to analog data.
DA conversion, analog signal transmission, analog signal reception, and AD
conversion are all performed by a modem (modulator/demodulator) in the control
circuit. A modem consists of a Network Control Unit (NCU) for connecting to the
telephone line and an A/D conversion unit for performing DA and AD conversions.
FAX System (Detail)
Scanner
Scanning
Lamp
Control Circuit
DA
Conversion
(Modulation)
Control Circuit
AD
Conversion
(Demodulation)
Printer
Printing
Original
CCD
Digital Signal
Modem
A/D Conversion
Unit
Analog Signal
Telephone Line
Modem
NCU
A/D Conversion
Unit
Digital Signal
Print
Theory of Operation
Black becomes 0,
Original
white 1 creating...
1 1 1 1 1 1
1 0 0 0 0 1
1 0 1 1 1 1
1 0 1 1 1 1
1 0 0 0 1 1
1 0 1 1 1 1
1 0 1 1 1 1
1 0 0 0 0 1
1 1 1 1 1 1
Image Digital data
Sending FAX
Receiving FAX
s6128-060
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