| 摘要 |
PURPOSE:To remove foreign matters without disk damage due to a frequent increase in stylus pressure by using a decrease in the level of a reproducing output and the increase of a dropout detection signal together and increasing the stylus pressure for the early removal of the foreign matter. CONSTITUTION:Variation in a reproducing output and a level drop due to the interposition of foreign matter are detected by a level holder 9, an attenuator 10, and a comparator 11. On the other hand, a dropout due to the interposition of the foreign matter is detected 19, and a signal increase is integrated and compared 21 with a specific value to generate a signal when the integral value is larger. Two kinds of foreign matter detection outputs are added 23 and a stylus pressure increases signal 14 is added 14 thereto. The interposition of the foreign matter is detected in a variety of cases, i.e. from a decrease in the output level of the reproducing signal, the increase of the dropout detection signal, etc., but this constitution detects the interposition of the foreign matter accurately in the early stage and decreases the number of times of an increase in stylus pressure, thereby removing the foreign matter completely without damaging a disk surface.
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