1 ) Key Switch And Led Display Matrix - Kyocera Mita DC-2560 Service Manual

(1) Key switch and LED display matrix
ASIC
Scan signals
(KS0~KS7)
Return signals
(KIN0~KIN4)
Scan signals
(DEG0~DEG7)
LED display signals
(SEG0~SEG15)
(LED lights terminal)
Figure 2-3-18 Key switch and LED display matrix
The key switches are laid out as a matrix and scan signals are constantly input from the
scan signal terminals (KS0 - KS7).
When some key switch of the key switch matrix is pressed, at a point of time when the
scan signal of the switch goes low level, a low return signal is sent to the return signal
terminals (KIN0 - KIN4) of the ASIC.
The controller ASIC (IC1) determines which switch is pressed by the scan signal
terminal output low level and the return signal terminal that signal is returned.
The LEDs are laid out as a matrix and scan signals are constantly input from the scan
signal terminals (DEG0 - DEG7).
The controller ASIC (IC1) output low level signal from a terminal of the LED display
signal terminals (SEG0 - SEG15) according to the information from the main PCB
(MPCB) and the LED of the line on which scan signals (DEG0 - DEG7) go high level is
lit, current flowing from the source driver.
Key switch
Key Switch section
5 V DC
7-segment LED
LED display section
Sink driver
Source driver
1AH
LED
2-3-17