23
R-90GCH
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) Tact switch circuit on the CPU unit.
(2) Control Unit (The control unit consists of Power unit
and CPU unit.)
The principal functions of these units and the signals
communicated among them are explained below.
Tact Switch Circuit
The tact switch circuit is composed of a matrix, signals
AN0-AN7 generated in the LSI are sent to the tact switches.
When a tact switch is touched, a signal is completed
through the tact switch circuit and passed back to the LSI
through PB0-PB3 to perform the function that was re-
quested.
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, reset circuit, buzzer circuit, tempera-
ture measurement circuit, relay watching circuit, input
voltage circuit and indicator circuit.
1) LSI
This LSI controls the temperature measurement signal,
tact switch strobe signal, relay driving signal and
indicator signal. And also LSI watches the relay
operation and the primary input voltage.
2) Power Source Circuit
This circuit generates the voltages necessary for the
control unit from the AC line 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 incorporates a very small error because it
works on commercial frequency.
4) Reset Circuit
A circuit to generate a signals which resetting the LSI
to the initial state when power is applied.
5) Buzzer Circuit
The buzzer is responds to signals from the LSI to emit
noticing sounds (tact switch touch sound and completion
sound).
6) 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.
7) Relay Operation Watching Circuit
This circuit watches so that the three (3) relays for the
top heating element, the side heating element and the
power transformer do not operate at the same time.
8) Input Voltage Watching Circuit
This circuit watches the primary input voltage.
9) Door Sensing Switch
A switch to inform the LSI if the door is open or closed.
10) Relay Circuit
To drive the magnetron, heating element, fan motor,
convection motor, damper motor, turntable motor and
light the oven lamp.
11) 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 10-digits, 42-segments
are used for displaying figures.
12) LED Circuit
A circuit to drive the Light-emitting diodes ( LD1-LD11).
13) Damper Switch
A switch to tell the LSI if the damper is open or close.
DESCRIPTION OF LSI
The I/O signals of the LSI are detailed in the following table.
Pin No.
Signal
I/O
Description
2
AN4
OUT
Tact switch strobe signal. ....................... Signal applied to tact switch section.
LED driving signal. ....... Signal is applied to the Light-emitting diodes (LD4-5).
3
AN3
OUT
Tact switch strobe signal. ....................... Signal applied to tact switch section.
LED driving signal. ............ Signal is applied to the Light-emitting diode (LD3).
4
AN2
OUT
Tact switch strombe signal. .................... Signal applied to tact switch section.
5
AN1
OUT
Tact switch strobe signal. ....................... Signal applied to tact switch section.
LED driving signal. ............ Signal is applied to the Light-emitting diode (LD2).
6
AN0
OUT
Tact switch strobe signal. ....................... Signal applied to tact switch section.
LED driving signal. ............ Signal is applied to the Light-emitting diode (LD1).
