发明授权
US4855983A Apparatus for recording and reading an optical disk, having reduced
offset in its tracking error signal
失效
用于记录和读取光盘的设备,其跟踪误差信号具有减小的偏移
- 专利标题: Apparatus for recording and reading an optical disk, having reduced offset in its tracking error signal
- 专利标题(中): 用于记录和读取光盘的设备,其跟踪误差信号具有减小的偏移
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申请号: US128279申请日: 1987-12-03
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公开(公告)号: US4855983A公开(公告)日: 1989-08-08
- 发明人: Shigeru Arai
- 申请人: Shigeru Arai
- 申请人地址: JPX Kawasaki
- 专利权人: Fujitsu Limited
- 当前专利权人: Fujitsu Limited
- 当前专利权人地址: JPX Kawasaki
- 优先权: JPX61-289549 19861203
- 主分类号: G11B7/085
- IPC分类号: G11B7/085 ; G11B7/09 ; G11B7/095
摘要:
A push-pull type tracking error signal produced by reflected light from pits on an ID area of an optical disk is averaged and sampled during a period while a light spot is scanned over the ID areas. An averaged value of a signal representative of the reflected light is stored for each sector of the disk, this value being a first sampled tracking error signal. The tracking error signal is also sampled while the light spot is scanned over a vacant zone having no pits in a data area, storing a second sampled tracking error signal. This vacant zone to be sampled is located either before or after a sequence of data bits in each sector. The first sampled tracking error signal is smaller than the second sampled tracking error signal because of the AC component produced by the pits. Thus, when an offset of the tracking exists, though the tracking error signal is kept almost zero by the servo control, the first sampled tracking error signal is not zero. Therefore, differences between the two tracking error signals indicates the amount of the offset. This offset signal may be visually monitored for adjusting the offset of the apparatus, or may be fed back for the tracking servo. The invention can be applied to a disk format having no mirror mark. The circuit of the invention is simple and inexpensive, because no high frequency need be output.