Sharp R-961 (W) - Page 25

TOUCH
CONTROL
PANEL
ASSEMBLY
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OUTLINE OF TOUCH CONTROL PANEL
The touch contro! 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 signals communi-
cated 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 from P11 - P17.
When a key padis touched, a signal is completed through the
key unit and passed back to the LSI through P20 - P23 to
perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, synchroniz-
ing signal circuit, ACL circuit, buzzer circuit, temperature
measurement circuit, relay circuit, indicator circuit, absolute
humidity sensor circuit, and back light 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 voltage necessary in the control
unit.
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Symbol Voltage
VG -5.2V
Application
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) ACL
A circuit to generate a signals which resets the LSI to the
initial state when power is supplied.
5) Buzzer Circuit
R-961 - 23
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion sound).
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, heating element, convection fan
motor, fan motor, turntable motor and light the oven lamp.
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8
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Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1
- LD5).
9) Indicator Circuit
This circuit consists of 7-digits, 30-segments and 4-
common electrodes using a Liquid Crystal Display.
~—
10) Temperature 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 applies to LS|. The result of detecting
is given to LSI controlling the relay and display.
11) Damper Switch
A switch to tell the LSI if the damper is open or close.
12) Absolute Humidity Sensor Circuit
This circuit detects the humidity of the food which is being
cooked, to control its automatic cooking.