R-890SLM
9 - 1
CHAPTER 9. CONTROL PANEL ASSEMBLY
[1] OUTLINE OF CONTROL PANEL
The control section consists of the following units as shown in
the control panel circuit.
(1) Jog Switch Unit
(2) Control Unit
The principal functions of these units and signals communicated
among them are explained below.
1. Jog Switch Unit
The jog switch unit is composed of a matrix, signals generated
in the LSI are sent to the jog switch unit from P42 – P45.
When a button is touched, a signal is completed through the jog
switch unit and passed back to the LSI through P00, P20, P21
and P22 to perform the function that was requested.
2. Control Unit
Control unit consists of LSI, power source circuit, synchronizing
signal circuit, reset circuit, buzzer circuit, indicator circuit,
encoder circuit, potentiometer circuit, temperature measurement
circuit and back light circuit.
1) LSI
This LSI controls the temperature measurement signal, tact
switch 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 (tact switch touch sound and completion
sound).
6) Stop Switch
A switch to “tell” the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, top and bottom heating element,
convection motor, fan motor, turntable motor, touch control
transformer and light the oven lamp.
8) Encoder
The encoder converts the signal generated by LSI into the
pulse signal, and the pulse signal is returned to the LSI.
9) Potentiometer Circuit
The circuit makes setting of the cooking mode by variable
resistance.
10) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1 -
LD10).
11) Indicator Circuit
This circuit consists 7-digits, 27-segments and 4-common
electrodes using a Liquid Crystal Display.
12) 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.
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Содержание R-890SLM
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