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131. 发明专利

JPH07307040A MAGNETO-OPTICAL RECORDING MEDIUM AND METHOD FOR REPRODUCING INFORMATION RECORDED IN SAME 失效
公开(公告)号：JPH07307040A
公开(公告)日：1995-11-21
申请号：JP22327794
申请日：1994-09-19
申请人： FUJITSU LTD
发明人： TAMANOI TAKESHI , IZUMI HARUHIKO , SUGIMOTO TOSHIO , MATSUMOTO KOJI , MIHARA MOTONOBU , MORITSUGU MASAHARU , MAEDA KIYOMITSU
IPC分类号： G11B11/10 , G11B7/125 , G11B7/126 , G11B11/105
摘要： PURPOSE:To obtain a magneto-optical recording medium capable of reproducing a signal with high resolving power without requiring a reproducing magnetic field. CONSTITUTION:This magneto-optical recording medium has a transparent substrate, a reproducing layer 18, a switching layer 20 and a recording layer 22 successively laminated on the substrate. The reproducing layer 18 is a perpendicularly magnetized film at room temp. but becomes an intrasurface-magnetized film when heated to a prescribed temp. or above. The switching layer 20 and the recording layer 22 are perpendicularly magnetized films. The layers 18, 20, 22 satisfy the relation of Tc1>Tc3>Tc2 (where Tc1, Tc2 and Tc3 are the Curie temps. of the layers 18, 20, 22, respectively). When this recording medium is irradiated with reproducing laser beams, in a high temp. region heated to the Curie temp. of the switching layer 20 or above, switched connection between the reproducing layer 18 and the recording layer 22 is broken and the layer 18 exhibits intrasurface magnetization. A mask is formed in the high temp. region without applying a reproducing magnetic field and data can be read from a low temp. region in a spot of the beams.

132. 发明专利

JPH07264069A ANALOG/DIGITAL CONVERSION UNIT AND SIGNAL PROCESSING SYSTEM USING THE UNIT 失效
公开(公告)号：JPH07264069A
公开(公告)日：1995-10-13
申请号：JP4754294
申请日：1994-03-17
申请人： FUJITSU LTD
发明人： TAGUCHI MASAKAZU , IZUMI HARUHIKO
IPC分类号： G06F3/05 , G11B20/14 , H03M1/12
摘要： PURPOSE:To provide an inexpensive analog/digital conversion unit capable of a high-speed sampling processing and to provide a signal processing system capable of a high-speed signal processing by using the analog/digital conversion unit. CONSTITUTION:This unit is provided with plural analog/digital conversion elements 8-1, 8-2, 8-3 and 8-4 for performing the sampling processing of input signals at different timings and a selector 18 for selecting and outputting respective digital values sampled in the plural analog/digital conversion elements 8-1, 8-2, 8-3 and 8-4 corresponding to a prescribed order. Also, a processing unit 14 performs an output rate processing from the selector 18 to the respective digital values outputted from the selector 18.

133. 发明专利

JPH07254188A RECORDING/REPRODUCING METHOD AND DEVICE FOR OPTICAL DISK 失效
公开(公告)号：JPH07254188A
公开(公告)日：1995-10-03
申请号：JP4614194
申请日：1994-03-16
申请人： FUJITSU LTD
发明人： IZUMI HARUHIKO , TAGUCHI MASAKAZU , TANAKA TSUTOMU
IPC分类号： G11B11/10 , G11B7/00 , G11B7/004 , G11B7/005 , G11B11/105
摘要： PURPOSE:To perform precise tracking control for an optical magnetic medium having large track pitches even when a light spot is made very small and to improve compatibility between optical magnetic media having different track pitches. CONSTITUTION:For an optical magnetic disk 1 having small recoding track pitches, an objective lens 14 is driven by an actuator 15 according to the detection result of a 4-division light detector 23 and a light spot is just focussed. However, for an optical magnetic disk 1 having large recording track pitches, by injecting offset into the detection result of the 4-divison light detector 23 and driving the actuator 15 so as to defocuss the light spot by a specified amount from a just focussed state, the objective lens 14 is positioned.

134. 发明专利

JPH07254182A MAGNETO-OPTICAL RECORDING MEDIUM 失效
公开(公告)号：JPH07254182A
公开(公告)日：1995-10-03
申请号：JP4419494
申请日：1994-03-15
申请人： FUJITSU LTD
发明人： IKETANI TOMONORI , TANAKA TSUTOMU , IZUMI HARUHIKO
IPC分类号： G11B11/10 , G11B7/257 , G11B11/105
摘要： PURPOSE:To obtain a magneto-optical recording medium having improved reproduction stability and C-N ratio by increasing the magnetic anisotropy of a magnetic film. CONSTITUTION:This magneto-optical recording medium consists of a transparent substrate 4, a 1st dielectric film 6b laminated on the substrate 4, a magnetic film 8 laminated on the 1st dielectric film 6b and a 2nd dielectric film 10 laminated on the magnetic film 8. Since the 2nd dielectric film 10 is made of a material different from that of the 1st dielectric film 6b and has film stress different from that of the 1st dielectric film 6b, the coercive force and magnetic anisotropy of the magnetic film 8 can be increased.

135. 发明专利

JPH07182801A OPTICAL DISK DATA REPRODUCING SYSTEM 失效
公开(公告)号：JPH07182801A
公开(公告)日：1995-07-21
申请号：JP33335693
申请日：1993-12-27
申请人： FUJITSU LTD
发明人： IZUMI HARUHIKO , TAGUCHI MASAKAZU
IPC分类号： G11B20/14 , G11B20/18
摘要： PURPOSE:To generate a correct reproduced data without being adversely affected by the changes in environmental temperature by detecting synchronizing signals from reproduced signals and generating data signals employing a maximum likelihood decoding system based on the sampling level of the reproduced signals. CONSTITUTION:Rising and falling edges of binary coded reproduced waveforms are detected by an edge detecting circuit 22 and front and back edges are outputted from respective PLLs 23 and 24 by synchronization clock. Moreover, respective maximum likelihood data detecting circuits 25a and 26b, which are synchronized to the synchronizing clocks, sample the level of reproduced waveforms and reproduced data are generated through an OR circuit 26 which generates data signals in accordance with a partial response maximum likelihood decoding system with the circuits 25a and 26b and a data distinguishing circuit 27. Due to the signal generation employing the synchronization clock based on the fluctuation of reproduced signal waveforms and the level signals, fluctuations in data conditions caused by environmental temperature fluctuation during a recording and sensitivity deviation of the recording medium are eliminated and reproduced data corresponding to correct recording of a recording medium are obtained.

136. 发明专利

JPH07182705A MAGNETO-OPTICAL MEDIUM AND ITS REPRODUCING DEVICE 失效
公开(公告)号：JPH07182705A
公开(公告)日：1995-07-21
申请号：JP32269393
申请日：1993-12-21
申请人： FUJITSU LTD
发明人： IZUMI HARUHIKO
IPC分类号： G11B11/10 , G11B11/105 , G11B20/10 , G11B20/14 , G11B27/30
摘要： PURPOSE:To obtain a magneto-optical medium which is a high-density magneto- optical medium (MSR medium) utilizing an ultra-resolution effect and attains the same recording line density in a magneto-optical recording part and a preformat recording parts. CONSTITUTION:Position recording to make the presence or absence of a recording mark 12 correspondent to '1' or '0' of data is executed in a recording track 11 of the magneto-optical recording part. Edge recording to make the presence or absence of the edges (front edge, rear edge) of a recording pit 11 correspondent to the '1' or '0' of the data executed in a recording track 13 of the preformat recording part. As a result, the recording line density in both recording parts is made the same.

137. 发明专利

JPH06267107A OPTICAL HEAD 失效
公开(公告)号：JPH06267107A
公开(公告)日：1994-09-22
申请号：JP5614893
申请日：1993-03-16
申请人： FUJITSU LTD
发明人： MIYABE KYOKO , TEZUKA KOICHI , IZUMI HARUHIKO
IPC分类号： G11B7/135 , G11B11/10 , G11B11/105
摘要： PURPOSE:To facilitate the arrangement of a shaping prism for shaping a laser beam in an optical head. CONSTITUTION:A laser diode 34 and a shaping prism 37 are provided on a head base 32. The shaping prism 37 is composed so that a surface formed by rotating a surface perpendicular to a laser beam around the axis orthogonal to the laser beam and parallel with the head base 32 is an incident surface 37-3. The shaping prism 37 is arranged by making the optical axis 37a coincide with the optical axis 34a of the laser diode 34.

138. 发明专利

JPH06195790A MAGNETO-OPTICAL DISK REPRODUCING DEVICE 失效
公开(公告)号：JPH06195790A
公开(公告)日：1994-07-15
申请号：JP34032492
申请日：1992-12-21
申请人： FUJITSU LTD
发明人： IZUMI HARUHIKO , TAGUCHI MASAKAZU
IPC分类号： G11B7/00 , G11B7/005 , G11B11/10 , G11B11/105 , G11B20/10
摘要： PURPOSE:To provide a magneto-optical disk reproducing device which reproduces information recorded on a magneto-optical disk by an edge recording system to output a stable high-quality reproduced waveform. CONSTITUTION:A differential amplifier circuit 34 fetches data recorded on a magneto-optical disk in a reproduced waveform through photodetectors 31a and 31b and current-voltage conversion circuits 32 and 33 and a comparator 35 binarizes and outputs the data at a prescribed slice level. When the data are outputted, an integration circuit 36 detects a DC or low-frequency component from the reproduced waveform at every sector. An offset correcting section 37 sets and holds an offset correcting voltage so that the output value of the circuit 36 can become zero and feeds back the voltage to the circuit 34.

139. 发明专利

JPH06195789A OPTICAL MEDIUM REPRODUCER 失效
公开(公告)号：JPH06195789A
公开(公告)日：1994-07-15
申请号：JP34032392
申请日：1992-12-21
申请人： FUJITSU LTD
发明人： TAGUCHI MASAKAZU , IZUMI HARUHIKO
IPC分类号： G11B7/00 , G11B7/005 , G11B11/10 , G11B11/105 , G11B20/10
摘要： PURPOSE:To avoid an offset and the effect of the saturation of a circuit system an optical medium reproducer reproducing information recorded on an optical medium such as an optical disk. CONSTITUTION:An ID(an information data) signal and an MO (a recording data) signal are detected from a regenerative waveform from the optical head 33 of a magneto-optic disk 32, and transmitted over an adding section 47 as the signals of high frequency components. On the other hand, the Mo signal of a low frequency component, from which an offset is eliminated by a compensating section 48 from the regenerative waveform, is extracted, and transmitted over the adding section 47. The MO signal of the low frequency component and the ID signal and MO signal of the high frequency component are added by the adding section 47, and digitized at the nest stage.

140. 发明专利

JPH06124496A MAGNETO-OPTICAL OVERWRITING DISK RECORDING AND PLAYBACK APPARATUS 失效
公开(公告)号：JPH06124496A
公开(公告)日：1994-05-06
申请号：JP27159192
申请日：1992-10-09
申请人： FUJITSU LTD
发明人： IZUMI HARUHIKO , MORITSUGU MASAHARU , TAGUCHI MASAKAZU
IPC分类号： G11B7/125 , G11B11/10 , G11B11/105
摘要： PURPOSE:To obtain a magneto-optical overwriting disk recording and playback apparatus wherein, when a mark (data) is recorded on a magneto-optical overwriting medium, the shift of a front edge and a rear edge in the mark is eliminated, a circuit constitution for executing the recording of the mark is made simple and a circuit can be made small-sized as a whole. CONSTITUTION:In an apparatus, a mark is recorded on, and erased from, a magneto-optical overwriting medium by two different magnetization processes which are changed according to a high-temperature process and a low- temperature process which are obtained by shining an optical beam according to recording data. In the apparatus, a pulse signal is generated by a data processing means 71 by synchronizing the recording data with a clock signal, and the duty ratio of a pulse is changed and output according to the mark recording part and the erasing part of the pulse signal. A switch means 47 is turned on/off according to its output data, a light-emitting means 39 is pulse- light-emitted by controlling a first light-emitting control means 38 and a second light-emitting control means 48, and the mark is recorded/erased.

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