Touch Control Panel Assembly - Sharp R-671(B)M Service Manual

TOUCH CONTROL PANEL ASSEMBLY

The touch control 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 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 through P23 - P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P74 - P77
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, indicator 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.
Symbol Voltage
VC -5V
OUTLINE OF TOUCH CONTROL PANEL
Application
LSI(IC1)
R-671M - 17
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
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, top heating element, bottom
heating element, fan motor, turntable motor and light
the oven lamp.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1 - LD4).
9) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.
10) Cooking Mode Indicator Circuit
A circuit to drive the Cooking Mode indicator (the light
emiting diodes LD6-LD9).