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CX-961
4) RFRP and RFCT signal circuit unit
The RFCT signal which is the difference signal between
the peak and bottom levels of the RF signal is
generated through head amplifier (IC201). RFRP and
RFCT can be monitored at TP203 (pin 20 of IC201
TA2150FN) and TP204 (pin 22 of IC201) respectively.
The TE, RFRP and RFCT signals are compared by a
hysteresis comparator inside IC301 (TC9495FP)
respectively and generate track information (TEZC
signal or RFZC signal). Based on this signal, the
traveling speed information about a lens disk is
generated and the number of tracks is counted.
Fig.5:RFRP AND RFCT SIGNAL CIRCUIT
5) SBAD signal circuit unit
This SBAD signal circuit unit outputs photodetector
output E and F from IC201 (pin 15 of TA2150FN) via an
addition amplifier assuming (E + F) as an SBAD signal.
This SBAD signal is used as the internal decision
conditions of focus ON/OFF with a focus error signal.
Further, the SBAD signal is also used for detecting
defects when disk scratches are passed.
Fig.6:SBAD SIGNAL CIRCUIT
5
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