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3. G3 FACSIMILE IMAGE TRANSMISSION
The following shows a block diagram of G3 facsimile image transmission.
Description of each block
(1) The document is converted to electrical signals by the contact sensor.
(2) After the document is converted, the electrical signals undergo A/D
(3) The binary image data is compressed by coding to reduce the size of
(4) The coded data is converted to analog signals modulated by the
(5) The modulated analog signals are demodulated by the MODEM on the
(6) The coded data is converted to binary image data by decoding.
(7) The binary image data is sent to the recording section to be printed.
This chapter describes (3) through (6).
(1) and (2) are described in Chapter 3, Reading Section, and (7) is
described in Chapter 4, Recording Section.
3.1
Structure of Image Signals
Reading of the image is performed in each scanline in the
ning
dots/mm. After one line is read, the next line is read at the pitch of the
tical scanning
3.85 lines/mm (standard mode), 7.7 lines/mm (fine mode) and 15.4 lines/
mm (super-fine mode). Reading is also possible at 16 dots/mm
(1)
Transmitting
Document
Contact
side
sensor
Receiving
(5)
From the line
side
Demodu-
lation
Fig. 5-1 Image Transmission by G3 Facsimile
conversion to be converted to digital binary image data.
the data to be sent as much as possible. The resulting data is coded
data.
MODEM, and is transmitted via the telephone line.
receiving side. The resulting data is digital coded data.
direction. The horizontal scanning line density is 8 dots/mm or 16
line density. There are three vertical scanning line densities:
G3 FACSIMILE COMMUNICATIONS
(2)
(3)
(4)
A/D
Coding
Modulation
conversion
(6)
(7)
Decoding
Recording
section
1
2
To the line
Received
image
3
4
5
6
ït
çi
horizontal scan-
ver-
15.4
5–3
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