| 摘要 |
PURPOSE:To attain the setting of a minimum required gain at respective time needed, by performing a relative movement between an optical beam spot, and the information track of an optical information recording medium at different speed, and switching a tracking servo gain an/or a focusing servo gain at different speed time. CONSTITUTION:At a recording time, that is, when an output from an amplifier 121-1 passes through a point D, and is inputted to a driver 121-3, an automatic tracking (AT) gain is set so as to have an amplification degree of (gamma). And at a reproducing time, since the output from the amplifier 121-1 passes through a point C, and is inputted to the driver 121-3, the AT gain is formed in a shape that it is raised as a whole, as shown in (delta). The (delta) is decreased by setting a resistance value, etc., between the points C and D appropriately. In this way, the lowering of the dignity of a recording signal based on excessive sensitivity due to an excessive gain at a recording mode time can be prevented.
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