Touch Control Panel - Sharp R-450B Service Manual

R-450B
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power
Unit and LSI Unit).
The principal functions of these units and the signals
communicated 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 P20, P21,
P22, P23, P24, P25, P26 and P27.
When a key pad is touched, a signal is completed
through the key unit and passed back to the LSI
through AN8, AN9, AN10 and AN11 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, syn-
chronizing 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 45 segments and 5 common
electrodes using a Liquid Crystal Display.
LSI(IZA894DR)
The I/O signal of the LSI(IZA894DR) is detailed in the following table.
Pin No. Signal I/O
1 AN8 IN
2 AN9 IN
3 AN10 IN
4 AN11 IN
5 AVSS IN
6 TEST IN
7 X2 OUT
8 X1 IN
9 VSS IN
10 OSC1 IN
11 OSC2 OUT
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
Signal coming from touch key.
When either G12 line on key matrix is touched, a corresponding signal out of P20 - P27
will be input into AN8. When no key is touched, the signal is held at "H" level.
Signal similar to AN8.
When either G11 line on key matrix is touched, a corresponding signal will be input into AN9.
Signal similar to AN8.
When either G10 line on key matrix is touched, a corresponding signal will be input into AN10.
Signal similar to AN8.
When either G9 line on key matrix is touched, a corresponding signal will be input into AN11.
A/D converter power source voltage.
The power source voltage to drive the A/D converter in the LSI. Connected to VC.
Connected to VC.
Terminal not used.
Connected to GND.
Power source voltage: -5V.
The power source voltage to drive the LSI is input to VSS terminal. Connected to VC.
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to OSC1 terminal.
Internal clock oscillation frequency control output.
Output to control oscillation input of OSC2.
3) Power Source Circuit
This circuit generates voltages necessary in the con-
trol 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
VC -5V
4) Relay Circuit
A 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 (key 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
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
LD1- LD10).
Description
6
Application
LSI(IC1)