20
R-7A55(W)/(B)
R-7E45(W)/(B)
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOIUCH CONTROL PANEL
The touch control section consists of the following
units
as shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit
The principal functions of these units and the signals
communicated 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
R20-R23. When a key pad is touched, a signal is
completed through the key unit and passed back to
the LSI through R82,R83 and R90-R93 to perform the
function that was requested.
Control Unit
Control unit consists of LSI, power source circuit,
synchronizing signal circuit, ACL circuit, buzzer circuit
and indicator circuit.
1) LSI
This LSI controls the key strobe signal, relay
driving signal for oven function and indicator signal.
2) Power Source Circuit
This circuit generates voltages necessary in the
control unit.
Symbol
Voltage
Application
VC
-5.1V
LSI(IC1)
VP
-26V
Fluorescent display tube :
Grid and anode voltage
VF1
2.9Vac
Filament of fluorescent
display tube
VF2
(VF1 to VF2 voltage)
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 Circuit
A circuit to generate a signals which resets the LSI
to the initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to
emit noticing sounds (key touch sound and
completionsound).
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, fan motor, turntable motor
and light the oven lamp.
8) Indicator Circuit
Indicator element is a Fluorescent Display.
Basically, a Fluorescent Display is triode having a
cathode, a grid and an anode. Usually, the cathode
of a Fluorescent Display is directly heated and the
filament serves as cathode.
The Fluorescent Display has 6-digits, 13-segments
are used for displaying figures.
9) Temperrature Measurement Circuit
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 result of detecting is given to LSI controlling
the relay and display.
10) Damper switch
A switch to tell the LSI if the damper is open or
close.
