21
DMT2420B
DMT2420R
DMT2420S
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
Symbol
Voltage
Application
VC
+5V
LSI(IC1)
9) Relay Circuit
A circuit to drive the magnetron, fan motor, turntable
motor and light the oven lamp.
10) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion sound).
11) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
It accompanies a very small error because it works
on commercial frequency.
12) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
13) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LED1 and LED2).
14) Absolute Humidity Sensor Circuit
This circuit detects moisture of the cooking food to allow
its automatic cooking.
15) Touch Screen
The touch screen is composed of a matrix, signal
generated in the LSI are sent to the key unit through P41,
P42, P43 and P44. When a key is touched, a signal is
completed through the touch screen and passed back to
the LSI through PB1, PB2, PB3, PB4 and PB5 to
perform the function that was requested.
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit and
LSI Unit).
The principal functions of these units and the signals commu-
nicated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals generated in the
LSI are sent to the key unit through P93, P94, P95 and P40.
When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through PB1, PB2, PB3,
PB4, PB5 and AN1 to perform the function that was re-
quested.
Control Unit
Control unit consists of LSI, IC, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchroniz-
ing signal circuit, key unit circuit, touch screen circuit,
absolute humidity sensor circuit and back light circuit.
1) IC1 (LSI)
This is a microcomputer, responsible for controlling the
entire control unit.
2) IC2
This is a read only memory IC, responsible for giving IC1
the all programmes.
3) IC3
This is an amplifier IC. This IC controls the contrast of
LCD and amplify the sensor signal.
4) IC4
This is a memory IC. This memorizes the contrast of LCD.
5) IC5
This IC drives the LCD.
6) ACL
This circuit generates a signal which resets the LSI (IC1)
to the initial state when power is supplied.
7) Indicator Circuit
This circuit consists of 100 x 160 dots using a Liquid
Crystal Display. The Liquid Crystal Display (LCD) is
drived by IC5.
8) Power Source Circuit
This circuit generates voltages necessary in the control
