| 摘要 |
<p>A device for playing a movie film, which effects the tracking control by reading a tracking pattern recorded in a movie film and, then, reads audio data to obtain RF signals, wherein the signal level of the RF signal output from a voltage-controlled variable-gain amplifier (VCA) (11) for adjusting the level of the RF signal is held in a first sample-and-hold (S/H) circuit (13), the average signal level of audio data of the RF signal is held in a second S/H circuit (16) through a low-pass filter comprising a resistor (14) and a capacitor (15), a difference detector circuit (18) which receives the output of the first S/H circuit (13) or the second S/H circuit (16) through a switch (17) detects the difference between the signal level of the output of the first or second sample-and-hold circuit (13 or 16) and a predetermined signal level, and the VCA (11) is so controlled that the difference decreases.</p> |
