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11. 发明专利

JPH02192038A OPTICAL DISK DEVICE IN FIXED OPTICAL SYSTEM 失效
公开(公告)号：JPH02192038A
公开(公告)日：1990-07-27
申请号：JP1141889
申请日：1989-01-19
申请人： FUJITSU LTD
发明人： MORITSUGU MASAHARU , SASAKI MASATERU
IPC分类号： G11B7/09
摘要： PURPOSE:To make unnecessary optical axis adjustment in a mobile part and a fixed part and to improve environment resistance by integrating the mobile part to trace the track of an optical disk medium and the fixed part to support an optical system. CONSTITUTION:The device consists of a mobile part 12, which has an actuator to trace an optical head to the track on the optical disk medium, and a fixed part 14, which provides a light source and an information detecting function and is fixed at the base of the optical disk device, and the mobile part 12 moves by the guide of a guide rail 15, and the mobile part 12 is linked to the fixed part 14 by a parallel light flux 7 emitted from the fixed part 14. Further the guide direction of the guide rail 15 is made correspond to the optical axis of a parallel light flux 7, and the guide rail 15 and the fixed part 14 are integrally composed. Consequently the optical axis emitted from the fixed part 14 corresponds to the moving axis of the mobile part 12, and the axis adjusting mechanism is made unnecessary. Thus the optical disk device of the fixed optical system at high reliability can be realized.

12. 发明专利

JPH02187901A BIAS MAGNETIC FIELD APPLYING METHOD FOR MAGNETO-OPTICAL RECORDING AND REPRODUCING DEVICE 失效
公开(公告)号：JPH02187901A
公开(公告)日：1990-07-24
申请号：JP818089
申请日：1989-01-17
申请人： FUJITSU LTD
发明人： MAKITA AKIHIKO , YAMADA TOMOYOSHI , MORITSUGU MASAHARU , TEZUKA KOICHI
IPC分类号： G11B11/10 , G11B5/02
摘要： PURPOSE:To avert the deterioration of recording data by turning a permanent magnet for impressing bias magnetic fields to a magnetic medium to a prescribed position according to modes,fixing the same to this position and selecting the direction where the magnetic fields are to be impressed. CONSTITUTION:The permanent magnet 26 for applying the bias magnetic fields 41, 42 on the recording medium 20 is turned and positioned according to the modes. The magnetic field 41 is applied in one direction perpendicular to the medium 20 at the time of recording. The magnetic field 42 is applied in the direction reverse therefrom at the time of erasing. The direction of the applied magnetic field 50 is determined in the direction orthogonal with the direction 51 of magnetization of the magnetic layer 22 of the medium 20 in the mode exclusive of recording and erasing. The magnetic field acting on the magnetic layer at the time of the mode exclusive of recording and erasing does not have the component in the direction where the magnetization direction of the magnetic layer is inverted according to this constitution. The inversion of the magnetization direction does not, therefore, arise even if a laser beam is strong at the time of reproducing or disturbance acts at the time of erasing. The deterioration of the recording data is thus prevented.

13. 发明专利

JPH02152022A FOCUS ERROR DETECTION SYSTEM 失效
公开(公告)号：JPH02152022A
公开(公告)日：1990-06-12
申请号：JP30542388
申请日：1988-12-02
申请人： FUJITSU LTD
发明人： MORITSUGU MASAHARU , TEZUKA KOICHI
IPC分类号： G02B7/28 , G11B7/09 , G11B7/135
摘要： PURPOSE:To prevent an influence of the change of the optical axis of an optical system or the like by providing a phase element inclined at a prescribed angle to the optical axis and a polarization state detector on the optical axis of a reflected beam and obtaining a focus error signal in accordance with the difference between two outputs of photodetectors. CONSTITUTION:The reflected beam from an optical disk 5 is transmitted through a quarte-wave plate 55 and its polarization state is changed, and the transmitted light and the separated light of a polarizing beam splitter 56 are uniform and light intensity distributions on photodetectors 57 and 58 are uniform, and the focus error signal is zero. When the optical disk 5 is moved away from an objective lens 1, the light intensity on detecting parts 57b and 58b of photodetectors 57 and 58 is higher and the focus error signal is negative; but when the optical disk 5 approaches the objective lens 1, the light intensity on detecting parts 57a and 58a is higher and the focus error signal is positive. Thus, since the reflected beam reaches photodetectors 57 and 58 without being converged and the spot diameter is increased, an influence of the change of the optical axis or the like upon the focus error signal is reduced to detect the focus error signal of high precision.

14. 发明专利

JPH01137432A OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE 失效
公开(公告)号：JPH01137432A
公开(公告)日：1989-05-30
申请号：JP29393187
申请日：1987-11-24
申请人： FUJITSU LTD
发明人： MORITSUGU MASAHARU , OZAWA YASUYUKI , NIMATA AKIO
IPC分类号： G11B11/10 , G11B7/09 , G11B11/105
摘要： PURPOSE:To simplify an optical system and the adjustment of an optical detector by bisecting one part of the optical detector, equipping an aperture before each optical detector, detecting a focusing error signal from the difference in two optical detectors and obtaining a tracking error signal from the difference in the outputs of the bisected optical detectors. CONSTITUTION:The means 30 bisecting the reflection light emitted from an information recording medium 27 and a condensing means 29 are equipped at a light spot control signal and information signal reproducing part. The light detectors 34, 35 receiving the light flux divided respectively are owned, one part 34 of the light detector thereof is bisected and apertures 32, 33 are equipped at the front of the respective light detector 34, 35. A focusing error signal is detected from the difference in the outputs of two light detectors 34, 35 and the tracking error signal is obtd. from the difference in the outputs of the bisected light detector 34. A servo-detection system and information signal detection system can be served as well by one optical system and the adjustment of the light detector is thus simplified as well as the simplification of the optical system.

15. 发明专利

JPH01112572A CLOCK SIGNAL GENERATING CIRCUIT IN OPTICAL DISK DEVICE 失效
公开(公告)号：JPH01112572A
公开(公告)日：1989-05-01
申请号：JP26997587
申请日：1987-10-26
申请人： FUJITSU LTD
发明人： OZAWA YASUYUKI , NIMATA AKIO , MORITSUGU MASAHARU
IPC分类号： H03L7/22 , G11B19/06 , G11B20/14 , G11B27/10
摘要： PURPOSE:To obtain a clock signal phase-locked to a clock bit reproducing signal quickly by comparing each output signal of two frequency dividers with output signals of a unique distance detector and a rotary encoder respectively by two phase comparators. CONSTITUTION:A pulse output synchronously with the phase of a reproducing signal of a clock bit from a unique distance detector 13 detecting the unique distance based on a reproducing signal and a clock signal from an optical head 12 and an output signal from the 1st frequency divider 33 are phase- compared by a phase comparator 29. On the other hand, the phase of an output rotary pulse from a rotary encoder 28 and the phase of an output signal from the 2nd frequency divider 34 are compared by a phase comparator 30. Output signals of the phase comparators 29, 30 are added by an adder 31 as a control signal and the result is fed to a variable frequency oscillator 32 and its output clock signal is subject to variable control.

16. 发明专利

JPS63268170A TRACK SERVO SYSTEM FOR OPTICAL DISK DEVICE 失效
公开(公告)号：JPS63268170A
公开(公告)日：1988-11-04
申请号：JP10286887
申请日：1987-04-24
申请人： FUJITSU LTD
发明人： OZAWA YASUYUKI , SUZUKI HIROSHI , MORITSUGU MASAHARU
IPC分类号： G11B7/085 , G11B21/08 , G11B21/10
摘要： PURPOSE:To obtain a servo system stable at the time of fine controlling by using the positional signal of a target track, a positional integral signal obtained from said positional signal, and the speed signal of an actuator as control elements. CONSTITUTION:A speed sensor 17 detects the absolute velocity of a track actuator 6 and transmits a signal to an amplifier 13. An error detection circuit 11 outputs a phase error signal to the amplifier 13. A positional error signal is generated by correcting the low frequency characteristic of a feedback signal through an integrating circuit 18. In such a way, the degrading of said characteristic caused by use of the absolute speed of the track actuator 6 as a speed signal is compensated. The above-mentioned speed, positional, and integrated position signals are inputted to the amplifier 13 for adding therein to control a drive coil current for the track actuator 6. As a result, a servo system stable at the time of fine controlling can be obtained.

17. 发明专利

JPS63171459A MAGNETO-OPTICAL RECORDER 失效
公开(公告)号：JPS63171459A
公开(公告)日：1988-07-15
申请号：JP280687
申请日：1987-01-08
申请人： FUJITSU LTD
发明人： SUZUKI HIROSHI , NIMATA AKIO , OZAWA YASUYUKI , MORITSUGU MASAHARU , INOUE KAZUHIKO , SATO SHINICHI
IPC分类号： G11B11/10 , G11B11/105
摘要： PURPOSE:To attain access to both sides and to decrease waiting time by providing an optical head to at least one of coils arranged on a magneto-optical disk medium to improve the simplicity and the transfer speed. CONSTITUTION:A coil generating an external magnetic field is separated, a coil 8 generates an upward magnetic field 5 and data is recorded on a medium recording layer 7a by using an optical head 3. A coil 9 generates a downward magnetic field 6 conversely and the data is recorded on the medium recording layer 7a by using the optical head 3. In applying changeover control so as to cause either external magnetic field in this way, the titled device is driven by one power supply.

18. 发明专利

JPS6344342A OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE 失效
公开(公告)号：JPS6344342A
公开(公告)日：1988-02-25
申请号：JP18909086
申请日：1986-08-12
申请人： FUJITSU LTD
发明人： MORITSUGU MASAHARU , OZAWA YASUYUKI , NIMATA AKIO
IPC分类号： G11B7/135 , G11B11/10 , G11B11/105
摘要： PURPOSE:To increase the wavelength margin of an optical filter and to facilitate the manufacture by using the light of one side light source for recording and erasing and the light of other light source for reproducing, in a light magnetic disk device to use two light sources of a different wavelength. CONSTITUTION:The light beam emitted from semiconductor lasers 1 and 5 comes to be a parallel light flux, is made incident on round correcting prisms 3 and 7, is made incident on beam splitters 4 and 8 and respectively emitted as light beams 22 and 21. A light beam 21, in which a light beam 22 is polarized by a reflecting mirror 10, is made incident on an optical filter 11 and irradiates the surface of media 14. The reflected light beam arrives at an optical filter 11, is separated, one side reproducing light is made incident on a polarizing beam splitter 17, separated, is made incident on a four-divided light detecting device 20 and outputted as the reproducing signal and the focus error. On the other hand, the light reflected by the splitter 17 is outputted through a two- divided light detecting device 19 as the reproducing signal and the focus error signal. A magneto-optical signal H can be obtained as the difference of two these reproducing signals.

19. 发明专利

JPS6310327A TRACKING SERVO SYSTEM FOR OPTICAL DISK DEVICE 失效
公开(公告)号：JPS6310327A
公开(公告)日：1988-01-16
申请号：JP15448486
申请日：1986-06-30
申请人： FUJITSU LTD
发明人： OZAWA YASUYUKI , NIMATA AKIO , MORITSUGU MASAHARU
IPC分类号： G11B7/09
摘要： PURPOSE:To perform a stable tracking servo by using a peak holding circuit to detect the extent of beam shift in accordance with the reflected light from a part where there are no information pits in a preformat part and eliminating the extent of beam shift, which is held in a sample holding circuit, from a following-up error electrically or mechanically. CONSTITUTION:The quantity of reflected light from the part where there are no pits in an ID part is held by peak holding circuits 3-1 and 3-2 inserted between a two-divided photodetector 1 and a second differential amplifier 4 and the difference between the quantity of reflected light held in the circuit 3-1 and that in the circuit 3-2 is detected by a second differential amplifier 4 to output a signal from the no-pit part, namely, a signal proportional to the extent of beam shift through the ID section. This signal proportional to the extent of beam shift is inputted to a sample holding circuit 5. The extent of beam shift outputted from the sample holding circuit 5 is subtracted from the extent of following-up error including beam shift outputted from the first differential amplifier 2 to obtain the extent of essential following-up error, and this extent is fed back to a galvanomirror 7.

20. 发明专利

JPS62266752A OPTICAL HEAD FOR MAGNETO-OPTICAL RECORDING 失效
公开(公告)号：JPS62266752A
公开(公告)日：1987-11-19
申请号：JP11170186
申请日：1986-05-14
申请人： FUJITSU LTD
发明人： OGAWA KOICHI , MORITSUGU MASAHARU
IPC分类号： G11B11/10 , G11B11/105
摘要： PURPOSE:To facilitate the manufacture and to improve the mass-productivity, and to perform phase compensation without any hindrance to the shape of an optical head by providing a wavelength late composed of a diffraction grating to a reproducing circuit for a magneto-optical recording medium. CONSTITUTION:The reproducing circuit is provided with the wavelength plate 8 composed of the diffraction grating and this plate 8 is used as a holographic wavelength plate where a P wave having its oscillation plane on the incident surface and an S wave having its oscillation plane perpendicular to the incident surface are lambda/n out of phase with each other. When this is used as an optical head for magneto-optical recording, the phase difference between the P and S waves of a reproduction optical system is measured previously to determine the plate 8 and, for example, when the S wave is delayed lambda/8 behind the P wave, the plate 8 where the S wave is lambda/8 precedent to the P wave is used. Thus, the manufacture is facilitated to improve the mass-productivity and the phase compensation is so performed without any hindrance to the shape of the optical head for recording.

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