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)Relay Unit
(2)Key Unit
(3)Control Unit
The principal functions of these units and the signals communicated among them are explained below.
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Relay Unit
Relay unit consists of six relays (RYI
(RD914BlU)
Key Unit
The key unit is composed of a matrix, signals generated in the LSI are sent to the key unit through E7,E8, El 1
When a key pad is touched, a signal is completed through the key unit and passed back to the LSI through
(RD913Al U)
Control Unit
Control unit consists of LSI, power source circuit, synchronizing signal circuit, ACL circuit, buzzer circuit, temperature measurement circuit, absolute humidity sensor circuit and indicator circuit.
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LSI
This LSI controls the temperature measurement signal, AH sensor signal, key strobe signal, relay driving signal for oven function and indicator sig- nal.
(RD916Al U)
Power Source Circuit
This circuit generates voltages necessary in the control unit.
Symbol Voltage Application
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.
(RD918Al U)
4)ACL Circuit
A circuit to generate a signal which resets the LSI to the initial state when power is supplied.
(RD919Al U)
5)Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit noticing sounds (key touch sound and completion sound).
(RD91 AA1 U)
6) Temperature Measurement Circuit: Oven temp.
The temperature in the oven cavity is sensed by the thermistor.
The variation of resistance according to sensed temperature is detected by the temperature meas- urement circuit and the result applied to LSI.
The result of detecting is given to LSI controlling the relay and display.
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7) Absolute Humidity Sensor Circuit
The circuit detects absolute humidity of a food which is under cooking, to allow its automatic cooking.
(RD91 GA1 U)
8)Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
(RD91 BAZU)
9)Relay Circuit
To drive the magnetron, heating element, fan mo-
tor, convection motor,damper motor, turntable motor and light the oven lamp.
(RD91 CBI U)
VC
it +0.5v
VP
VFI
VF2
LSI (ICI ), ACL circuit and tem- perature measurement circuit Buzzzer circuit and IC2
IC2
Fluorescent display tube : Grid and anode voltage
Filament of fluorescent display tube
VFI - VF2 voltage
(RD917Al U)
10) 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
(RD91 DA1 U)
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