Canon fax basic 2000 서비스 매뉴얼

FACSIMILE SYSTEM

6–18

4. OPCNT BOARD

As the operation panel is the part that the user must touch to operate the

facsimile, the OPCNT board in the operation panel is powered ON at all

times to enable use of buttons on the operation panel.

The OPCNT board is configured as follows:

Fig. 6-18   Conceptual View of OPCNT Board

The OPCNT control IC on the OPCNT board performs serial communica-

tions with the system controller on the SCNT board. After this, serial/par-

allel conversion is performed by the system controller, and the signals are

relayed to the MPU.

The following are the main functions of the OPCNT board:

• Detection of button input

• LED lighting control

• Display indication control

4.1

Detection of Button Input

The OPCNT board detects pressing of the buttons on the operation panel,

and relays this to the SCNT board. Many buttons are provided on the top

surface of the operation panel. If one switch were used for one button,

many input ports would be required for the OPCNT control IC that is con-

nected before the operation panel. For this reason, button input is detected

using a matrix system to prevent an increase in the number of input ports.

The button detection circuit is configured as follows.

Parallel bus

System

controller

SCNT board

Serial bus

OPCNT

control IC

OPCNT board

MPU

Keyboard