Touch Control Panel Assembly - Sharp R-967 Service Manual

The touch control section consists of the following units as
shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit (The Control unit consists of Power unit
and CPU unit.)
The principal functions of these units and signals commu-
nicated 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 P10, P11, P12, P13,
P14, P15, P16 and P17.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P70, P71,
P72 and P73 to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, ACL circuit, buzzer circuit, relay
circuit, temperature measurement circuit, indicator circuit,
absolute humidity sensor circuit and back light circuit.
1) LSI
This LSI controls the temperature measurement sig-
nal, absolute humidity sensor 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
VC -5.2V
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 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 (Stop Switch)
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, grill heating element, convec-
tion heating element, convection motor, fan motor,
turntable motor, damper motor, touch control trans-
former and light the oven lamp.

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL
Application
LSI(IC1)
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD10 - LD19).
9) Indicator Circuit
This circuit consists 40-segments and 16-common
electrodes using a Liquid Crystal Display.
The Liquid Crystal Display (LCD) is drived by LCD
driver IC3.
10) 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.
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.
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