Sharp JC-K99 - Page 14

JC-K99
©
CIRCUIT
DESCRIPTION
¢ Remote control operation
The remote control unit employs a voltage comparison sys-
tem, and the main operation principles are described below.
(See Fig. 15—1.)
1. Before a switch on the remote control unit is pressed, vol-
tages (pin 15: 1.49 V, pin 14: 0.75 V, pin 16: ‘‘H"’) are
output to each terminal of voltage comparator IC4.
2. When any remote control switch is pressed, a pulse approx.
8 msec wide is generated by pulse-generating circuits 019
and Q20, and is input to pin 15 of mechanism controller
microcomputer of IC5.
The voltage of pin 15 of voltage comparator IC4 is as shown
in Fig. 15—2.
3. When the pulse is input to pin 15 of IC5, ““L —> H’" is out-
put from pin 1 only while the unit is in the stop or standby
mode. While the unit is operating, ‘‘H’’ is output. This sets
voltage comparator IC4 to the operation mode.
The input terminal voltage of IC4 becomes pin 15 < pin
14 when any switch is pressed, and ‘‘L’’ is output from pin
16. This output signal is input to pin 5 of IC5. When the
pulse input to pin 15 of IC5 rises, the internal counter starts,
and a control signal is output to terminals H1 ~ H4 accord-
ing to the timing shown in Fig. 15—3.
4. Terminals H1 ~H4 are output to pin 14 of IC 4, and the volt-
age of step state shown in Fig. 15—4 is input by the com-
parison voltage generating circuit.
5. Voltages of pins 15 and 14 of IC4 fluctuate as follows:
(See Fig. 15—4.)
@ When X-BASS is pressed and H1 outputs ‘’L’’.
@ When FF/REW is pressed and H2 outputs ‘’L’’.
@ When STOP is pressed and H3 outputs “’L’’.
(4) When PLAY is pressed and H4 outputs ‘‘L’’.
According to voltage comparator IC4 (pin 15 > pin 14),
“H"’ is output, and the internal counter stops.
When “‘L’’ — “'H"’ is input to pin 5 of IC5, the extent to
which the output of H1 ~H4 becomes ‘‘L"’ is detected to
determine which switch is being pressed.
FF/REW
e If no button is pressed within 600 msec after the FF/REW
button is pressed, the unit enters the FF mode.
(See Fig. 15—5.)
e When the FF/REW button is pressed a second time within
600 msec, the unit enters the REW Mode. (See Fig. 15-6.)
Reverse mode
e When the PLAY/DIR button is pressed a second time with-
in 600 msec, the unit plays in the >mode. (See Fig. 15—5.)
e The mode playback remains in the DIRECTION (press the
PLAY/DIR button), AUTO REWIND or SKIP REVERSE mode
and is cancelled when the unit stops. (See Fig. 15—6.)
e For any other playback, the unit enters the mode.
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