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1. 发明授权

US06868052B2 Optical disc playback apparatus and method of judging disc type 失效
标题翻译：光盘播放装置及光盘类型判断方法
公开(公告)号：US06868052B2
公开(公告)日：2005-03-15
申请号：US09849493
申请日：2001-05-07
申请人： Mitunori Konno , Masato Nagasawa , Mituru Umazaki
发明人： Mitunori Konno , Masato Nagasawa , Mituru Umazaki
IPC分类号： G11B7/004 , G11B7/09 , G11B7/12 , G11B7/13 , G11B19/12 , G11B7/00
CPC分类号： G11B19/125
摘要： In a system using a pickup including a bifocal lens which is one lens having two focal points, mere judgment by the number of peaks of a focus error signal does not achieve a clear judgment of the type of an optical disc, especially whether it is a CD or a DVD. Therefore, it is required to perform a judgment based on a difference in recording density of the optical disc. According to the present invention, when detecting a tracking error by the phase difference method, a pulse width limit circuit 35 in a tracking error detecting circuit 7 provides such limitations that a pulse of a width larger than a predetermined pulse width should not appear in a pulse train of a phase error signal. Disc type judgment is then performed for discs having different recording densities, for instance, whether it is a CD or a DVD, based on the phase error signal after the pulse width limitation or that before and after the pulse width limitation.
摘要翻译：在使用包括具有两个焦点的一个透镜的双焦点透镜的拾取器的系统中，仅通过聚焦误差信号的峰值数量的判断就不能清楚地判断光盘的类型，特别是是否是 CD或DVD。因此，需要基于光盘的记录密度的差进行判断。根据本发明，当通过相位差方法检测到跟踪误差时，跟踪误差检测电路7中的脉冲宽度限制电路35提供了这样的限制，使得宽度大于预定脉冲宽度的脉冲不应出现在相位误差信号的脉冲串。然后，基于脉冲宽度限制后的相位误差信号或脉冲宽度限制前后的相位误差信号，对具有不同记录密度的盘进行光盘类型判断，例如是CD还是DVD。

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