21
R-55TS
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units as
shown in the touch control panel circuit.
(1) Switch Unit
(2) Power Unit
The principal functions of these units and signals
communicated among them are explained below.
Switch Unit
The switch unit is composed of a matrix, signals generated
in the LSI are sent to the switch unit from P14 - P17.
When a key pad is touched, a signal is completed through
the switch unit and passed back to the LSI through P24 -
P27 to perform the function that was requested.
Encoder
The encoder convents the signal generated by LSI into the
plus signal, and the plus signal is returned to the LSI.
Power Unit
Power unit consists of LSI, power source circuit,
synchronizing signal circuit, ACL circuit, buzzer circuit,
relay circuit, temperature measurement circuit and indicator
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) Reset Circuit
A circuit to generate a signal 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
audible sounds (key touch sound and completion sound).
6) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, upper heater, lower heater, fan
motor, turntable motor and light the oven lamp.
8) Indicator Circuit
This circuit consists of 4-digits, 13-segments and 3-
common electrodes using a Liquid Crystal Display.
9) 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.