Canon fax basic 2000 サービスマニュアル

FACSIMILE SYSTEM

6–4

the DRAM and the MODEM, and between the system controller and the

DRAM to reduce the load placed on the CPU.

The system controller is the IC that controls 

 peripheral devices. It

converts the serial data that arrives from the reading section to parallel data

and performs chip selection of peripheral ICs, amongst other operations.

2.2

Communications Control Section

This section comprises a MODEM, and is connected to the system control

section by a 

. “MODEM” is an abbreviation of MOdulator/DEModula-

tor. The MODEM on a facsimile performs modulation for transferring the

image data to the telephone line, and demodulation of image data that has

been received. The modulation/demodulation method used complies with

 recommendations. Among its other functions, the MODEM also

 signals.

2.3

Reading Control Section

This section comprises an image processor IC and SRAM for buffering

read data. The image processor IC is connected to the system control sec-

tion via a bus.

After the document has been read by the contact sensor, the resulting

image data undergoes A/D conversion by the image processor IC in the

reading control section and image processing such as resolution conver-

sion in the 

 direction, and the resulting image data is

sent to the system controller in the system control section.

2.4

Printer Control Section

This section is functionally the same on both an LBP method or a BJ

printer method, though slightly different in some respects. This section

comprises an MPU, system control, DRAM and ROM independent of the

system control section, and handles control of the entire printer. (On an

LBP printer, this section is sometimes integrated as a one-chip microcom-

puter.) The printer control section merely transfers the printer status (status

of printer-related sensors, error status, etc.) to the system control section. It

is provided with an interface for receiving image data for printing, and

communicates with the system control section. Facsimile image data is

converted (resolution conversion, smoothing, etc.) to image data for print-

ing at the system control section.