R-234 (serv.man2). Part 1 Text (1-28) - Sharp Home Appliance Service Manual (repair manual). Page 18

R-234 - 18

 OUTLINE OF TOUCH CONTROL PANEL

To drive the magnetron, fan motor, turntable motor and
light the oven lamp.

The buzzer is responsive to signals from the LSI to emit
audible sounds (tact switch touch sound and completion
sound).

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.

A switch to "tell" the LSI if the door is open or closed.

The encoder converts the signal generated by LSI into
the pulse signal, and the pulse signal is returned to the
LSI.

A circuit to drive the back light (Light emitting diodes
LED1-LED3)

The touch control section consists of the following circuits as
shown in the touch control panel circuit.

The principal functions of these circuits and their related
signals are explained below.

Tact Switch
Signals generated in the LSI are sent to the tact switches
through R60, R61,R62 and R63.
When a tact switch is touched, a signal is completed through
the tact switch and passed back to the LSI through R81 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.

This circuit generates a signal which resets the LSI to the
initial state when power is supplied.

This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.

This circuit generates voltage necessary in the control unit
from the AC line voltage. In addition, the synchronizing
signal is available in order to compose a basic standard
time in the clock circuit.

Symbol

Voltage

Application

VC

+5V

LSI(IC1)