22
R-84ST -
TOUCH CONTROL
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion sound).
6) Door Sensing Switch (Stop Switch)
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, grill heating element, bottom
heating element, convection motor, fan motor, turntable
motor, touch control transformer and light the oven lamp.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1
- LD10).
9) Indicator Circuit
This circuit consists 7-digits, 39-segments and 3-common
electrodes using a Liquid Crystal Display.
10) Temperature Measurement Circuit : (OVEN
THERMISTOR)
The temperature in the oven cavity is sensed by the
thermistor. The variation of resistance according to
sensed temperature is detected by the temperature
measurement circuit and the result applied to LSI.
The LSI uses this information to control the relay
and display units.
The touch control section consists of the following units as
shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit (The Control unit consists of Power unit and
CPU unit.)
The principal functions of these units and signals communi-
cated 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 from P40, P41, P72, P73 P74, P75,
P76 and P77.
When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through P44 - P47 to
perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, synchroniz-
ing signal circuit, ACL circuit, buzzer circuit, relay circuit,
temperature measurement circuit, indicator circuit and back
light circuit.
1) LSI
This LSI controls the temperature measurement signal,
key strobe signal, relay driving signal for oven function
and indicator signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control
unit.
Symbol
Voltage
Application
VC
-5.2V
LSI(IC1)
3) 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.
4) ACL
A circuit to generate a signal which resets the LSI to the
