Led Display Circuit - Toshiba e-STUDIO520 Service Manual

4) Data transmission
FRAME
LOAD
FRAME
LOAD
CP
D0-D3
5.4.2

LED display circuit

Method of LED display
Example: Displaying "COPY"
COM1
OUTP5
The transistors (Q19 and Q1) are turned ON when the COM1 signal becomes Low level.
Also, when OUTP5 signal changes to Low level, the current flows from +5.1VA via the transistor (Q1) to
the LED10-1 (COPY) to turned ON the LED10-1.
Conditions to turn ON the LED
1) The transistor (Q1) connected to the LED anode is ON.
2) The transistor (Q7) connected to the LED cathode side is ON.
The LED is turned ON when 1) and 2) are satisfied.
e-STUDIO520/600/720/850 CONTROL PANEL
1/tF
240 1 2
Low
Q19
SG
240 1 2
CP x (640/4) pulses
Fig.5-8
+5.1VA
Current
G
Q1
(COPY)
LED10-1
Fig.5-9
5 - 16
1/tF
240 1 2
Low
Q7
SG
March 2005 © TOSHIBA TEC