Touch Control Assembly - Sharp R-244(W)M Service Manual

The touch control section consists of the following units.
(1) Switch Unit
(2) Control Unit
The principal functions of these units and the signals
communicated among them are explained below.
Switch Unit
The switch unit is composed of a matrix, signals generated
in the LSI are sent to the switch unit through R60, R61, R62
and R63.
When a switch button is touched, a signal is completed
through the switch unit and passed back to the LSI through
R81 and R83 to perform the function that was requested.
Control Unit
Control unit consists of LSI, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchroniz-
ing signal circuit and back light circuit.
1) ACL
This circuit generates a signal which resets the LSI to the
initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.
3) Power Source Circuit
This circuit generates voltage necessary in the control unit
from the AC line voltage.
Symbol Voltage
VC +5V
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
Application
LSI(IC1)
R-244M - 9
4) Relay Circuit
To drive the magnetron, fan motor, turntable motor and
light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (tact switch touch sound and completion
sound).
6) 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.
7) Door Sensing Switch (Stop Switch)
A switch to "tell" the LSI if the door is open or closed.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LED1-LED3)