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1. 发明专利

JP2001236660A FOCUS OFF-SET ADJUSTMENT METHOD 失效
公开(公告)号：JP2001236660A
公开(公告)日：2001-08-31
申请号：JP2000048905
申请日：2000-02-21
申请人： HITACHI LTD
发明人： SAITO ATSUSHI , SUGIYAMA HISATAKA , ITO MASAMICHI , TAKASAGO MASAHIRO
IPC分类号： G11B7/09
摘要： PROBLEM TO BE SOLVED: To shorten an adjusting time for an optical disk required to adjust a focus offset in a groove and a land and to adjust on a track that adjacent tracks are recorded by recording the number of minimum sectors. SOLUTION: The recording to plural continuous sectors holding a part that the groove and the land are connected in one place by one revolution therebetween is performed continuously by three tracks in the radial direction, and error information is obtained from the data recorded on the central track of three tracks.

2. 发明专利

JP2555859B2 失效
公开(公告)号：JP2555859B2
公开(公告)日：1996-11-20
申请号：JP31011693
申请日：1993-12-10
申请人： HITACHI LTD
发明人： MAEDA TAKESHI , TSUNODA YOSHITO , FUNO TAKAKAZU , TAKASAGO MASAHIRO , MIZOGUCHI YASUMITSU
IPC分类号： G11B7/09 , G11B7/00 , G11B7/004 , G11B7/0045 , G11B7/125 , G11B20/18

3. 发明专利

JP2523464B2 失效
公开(公告)号：JP2523464B2
公开(公告)日：1996-08-07
申请号：JP6241382
申请日：1982-04-16
申请人： HITACHI LTD
发明人： MIZOGUCHI YASUMITSU , TSUNODA YOSHITO , SENOO HIROMI , TAKASAGO MASAHIRO
IPC分类号： G11B7/00 , G11B7/004 , G11B7/12 , G11B7/125 , G11B7/126 , H01S5/042 , H01S5/068

4. 发明专利

JPH07121885A FOCUS CONTROL CIRCUIT FOR OPTICAL DISK DEVICE 失效
公开(公告)号：JPH07121885A
公开(公告)日：1995-05-12
申请号：JP26851293
申请日：1993-10-27
申请人： HITACHI LTD
发明人： ITO MASAMICHI , SAEGUSA SHOZO , TAKASAGO MASAHIRO
IPC分类号： G11B7/085 , G11B7/095
摘要： PURPOSE:To hold the stability of a focus control circuit at the time of seek operation. CONSTITUTION:In an optical disk device controlling an optical spot in the normal direction of a disk and in the radial direction of the disk, a detection means 3 detecting a high frequency detection 2 and a large amplitude detection 1 detecting signals with a high frequency component and a large amplitude components from a focus error signal to which the high frequency component and the large amplitude component of a track error signal are leaked in and a reduction means 4 eliminating the high frequency and large amplitude components form the focus error signal incorporating the leaking in high frequency and large amplitude components are provided. Thus, the counting of a track error is performed surely in the seek operation, and the focus control circuit at the time of seek operation is stabilized.

5. 发明专利

JPH06176378A SEEKING CIRCUIT FOR OPTICAL DISK DEVICE 失效
公开(公告)号：JPH06176378A
公开(公告)日：1994-06-24
申请号：JP32914192
申请日：1992-12-09
申请人： HITACHI LTD
发明人： ITO MASAMICHI , TAKASAGO MASAHIRO
IPC分类号： G11B7/085
摘要： PURPOSE:To cancel the eccentricity with a speed detection means in a single direction and to reduce the effect due to the reverse direction and the scale of a speed detection circuit by outputting a filter circuit output for a source obtained at a following time at a seeking time as a feed forward compensation value as well. CONSTITUTION:A laser beam 2 irradiates a disk l as a light spot 4 by an objective lens 3, and the signal 7 of a positional deviation amount is outputted from the return beam by a detector 27 and a differential amplifier 19. Fine, source actuators 5, 6 are drive controlled by amplifiers 19, 13 with the signals 10, 21 obtained through compensators 8, 15 and an adder 90 the signal 7. A speed command value is obtained by a counter 91, a ROM 64 and D/A and FV converters 70, 72 from the signal 7 at a seeking time, and a feed forward compensation value 20 obtained from the signal 21 at a following time is added to that. Further, the seeking is performed in the reverse direction even though in the detection in a single direction by a direction switching circuit 92. Thus, the effect due to the reverse direction and the scale of the speed detection circuit are reduced.

6. 发明专利

JPH065563B2 失效
公开(公告)号：JPH065563B2
公开(公告)日：1994-01-19
申请号：JP27093388
申请日：1988-10-28
申请人： HITACHI LTD
发明人： YOSHIDA AKIO , YOKOI YUKIKAZU , KANEDA NORYA , TAKASAGO MASAHIRO , KUSHIZAKI OSAMI
IPC分类号： G11B11/10 , G11B5/02 , G11B11/105

7. 发明专利

JPH04289559A DIGITAL DATA REPRODUCING METHOD 失效
公开(公告)号：JPH04289559A
公开(公告)日：1992-10-14
申请号：JP5464491
申请日：1991-03-19
申请人： HITACHI LTD , HITACHI VIDEO & INF SYST
发明人： TAKASAGO MASAHIRO , KAWASHIMA TORU , MATSUZAKI MASANORI , KON TOSHIHARU
IPC分类号： G11B20/10 , G11B20/18
摘要： PURPOSE:To correctly demodulate data bits even at the time when a reproduced clock signal is partially dropped out by a defect of a VFO part. CONSTITUTION:A defect part of a recording medium is detected based on a reproduced signal 1 by a defect detector 11; and if a defect part is detected, the cut-off characteristic of a loop filter 6b constituting a PLL circuit 6 has the band narrowed in comparison with that for normal reproducing and the loop gain is reduced to perform the reproducing processing. If read error occurs in the case of the digital data reproducing processing and the retry operation should be performed, the cut-off characteristic of the loop filter 6b has the band narrowed in comparison with that for reproducing of digital data where the read error occurs, and the loop gain is reduced.

8. 发明专利

JPH0451893B2 失效
公开(公告)号：JPH0451893B2
公开(公告)日：1992-08-20
申请号：JP13858281
申请日：1981-09-04
申请人： HITACHI LTD
发明人： MAEDA TAKESHI , MIZOGUCHI YASUMITSU , TAKASAGO MASAHIRO , KANEDA NORYA , TSUNODA YOSHITO
IPC分类号： G11B7/125 , H01S5/068 , H01S5/0683

10. 发明专利

JPH0332142B2 失效
公开(公告)号：JPH0332142B2
公开(公告)日：1991-05-10
申请号：JP7123382
申请日：1982-04-30
申请人： HITACHI LTD
发明人： MAEDA TAKESHI , TSUNODA YOSHITO , FUNO TAKAKAZU , TAKASAGO MASAHIRO , MIZOGUCHI YASUMITSU
IPC分类号： G11B7/00 , G11B7/004 , G11B7/0045 , G11B7/007 , G11B7/09 , G11B7/125 , G11B19/04 , G11B20/10 , G11B20/12 , G11B20/18 , G11B27/36

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