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3. DISPLAY CIRCUIT
3.1 Outline
The control panel of this printer has four LED lamps, one LCD display, and eight switches.
The control panel is connected to the Main PCB and its functions are as follows:
(1)
The LCD shows the printer status and error message in alpha-numeric characters.
(2)
The LED lamps indicate the operating conditions of the printer.
(3)
The printing mode and LCD brightness can be changed by switches.
LCD
3.2 Operation
Indicators on the control panel (LED lamps and LCD) are controlled by the video controller
circuit.
All the switch signals are input to the video controller circuit.
Signals Descriptions:
LED1 - LED4
PAD4 - PAD7 LCD control signal.
LCDRS
LCDE
SW1 - SW8
LED1
LED2
LED3
LED4
Main PCB
Figure 3.8 Display Circuit
On-off control for the respective LED lamps.
Illuminating when Low and extinguished when High.
A signal to distinguish PAD4 - PAD7 into command and data.
A signal to start the operation.
Input signals from the switches.
Going Low when each switch is pressed.
SW8
SW7
SW6
III - 11
SW5
SW4
SW3
SW2
SW1
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