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81. 发明专利

JPH07296421A OPTICAL DISK MEDIUM 失效
公开(公告)号：JPH07296421A
公开(公告)日：1995-11-10
申请号：JP12998995
申请日：1995-05-29
申请人： HITACHI LTD
发明人： KAKU TOSHIMITSU , TSUNODA YOSHITO , MAEDA TAKESHI , NAKAMURA SHIGERU
IPC分类号： G11B7/24 , G11B7/007
摘要： PURPOSE:To obtain exact tracking control signals by composing respective sectors of sector marks, reflection surface disposed behind these sector marks and additional recording regions after these reflection surfaces and forming the reflection surfaces by cutting a part of grooves. CONSTITUTION:This disk is composed of guide tracks 62 for guiding a light spot for recording and reproducing information and sector mark parts 64 for generating the timing to detect total reflection regions 63. The guide tracks 62 have the grooves of, for example, about lambda/8 depth and the reflected diffracted light distribution is changed by a positional relation of the incident spot on the guide tracks 62 and, therefore, the change is detected by bisected photodetectors and the respective signals are differentiated by a differential amplifier, by which the tracking signals are obtd.

82. 发明专利

JPH07105564A OPTICAL HEAD 失效
公开(公告)号：JPH07105564A
公开(公告)日：1995-04-21
申请号：JP24770793
申请日：1993-10-04
申请人： HITACHI LTD , HITACHI MAXELL
发明人： MUNEYOSHI YASUHIKO , NAKAMURA SHIGERU , SUENAGA MASASHI
IPC分类号： G11B7/135
摘要： PURPOSE:To additionally reduce the size and thickness of the optical head by constituting a beam separating means for separating a reflected beam and exit beam so as to commonly have a function of a polarizing means to bend the progressing direction of the exit beam by about 90 deg. and the beam separating means so as to contain the polarizing prism and polarizing circuit means. CONSTITUTION:The exit beam from a semiconductor laser 1 is polarized by a polarizing prism and is converted from linearly polarized light to circularly polarized light by passing a quarter-wave plate 6. The circularly polarized light is made incident on an information medium surface 5. The reflected beam 8 is converted from the circularly polarized light to the linearly polarized light when the beam passes the quarter-wave plate 6. At this time, the polarization direction of the reflected beam 8 is perpendicular to the polarization direction of the exit beam 7. The incident reflected beam 8 on the polarizing prism 21 is polarized in a direction exclusive of about 90 deg. from a relation between the polarization direction of the reflected beam 8 and the optical axis direction 22 of the double refractive crystal constituting the polarizing prism 21 when the reflected beam 8 is reflected by the reflection surface 23. The exit beam 7 and the reflected beam 8 are thus separated.

83. 发明专利

JPH0785523A MAGNETO-OPTICAL DISK DEVICE 失效
公开(公告)号：JPH0785523A
公开(公告)日：1995-03-31
申请号：JP23262493
申请日：1993-09-20
申请人： HITACHI LTD , HITACHI MAXELL
发明人： SUENAGA MASASHI , NAKAMURA SHIGERU , MUNEYOSHI YASUHIKO
IPC分类号： G02B7/18 , G02B7/182 , G11B7/135 , G11B11/10 , G11B11/105
摘要： PURPOSE:To make an optical system small in size and light in weight and also to reduce the number of positions to be adjusted. CONSTITUTION:A deformable Wollaston prism 6 as a polarized light separating optical element and a Faraday element 7 as an azimuth rotator are arranged between a semicondoctor laser 1 and an objective lens 3 in a pickup device 100 for an magneto-optical disk. Thus, the magneto-optical disk device is made small in size and light in weight. And also, the number of positions to be adusted is reduced.

84. 发明专利

JPH0772567A OPTICAL INFORMATION RECORDING MEDIUM AND OPTICAL INFORMATION RECORDING AND REPRODUCING DEVICE 失效
公开(公告)号：JPH0772567A
公开(公告)日：1995-03-17
申请号：JP22006093
申请日：1993-09-03
申请人： HITACHI LTD
发明人： SUGIYAMA HISATAKA , CHOKAI MINORU , NAKAMURA SHIGERU , WAKABAYASHI KOICHIRO , ARIMOTO AKIRA , IMAZEKI SHUJI , KOBAYASHI SETSUO
IPC分类号： G03C1/00 , G03C1/73 , G11B7/24 , G11B7/244
摘要： PURPOSE:To effectively micronize a light spot and to record and reproduce information at a recording density below optical resolution by arranging a photochromic layer using a specified photochromic material on the light irradiation side of a recording and reproducing layer. CONSTITUTION:A disk 6 of the optical information recording medium and optical information recording and reproducing device consists of a replica substrate 6a, a photochromic layer 6b, a recording and reproducing layer 6c, a reflecting layer 6d and a protective layer 6e. The photochromic layer 6b of the photochromic material has a light transmissivity increased with increase in incident power or incident energy density and saturated is arranged close to the recording and reproducing layer 6c, and a light spot with the incident power density increased at the center and decreased at the periphery is passed through the photochromic layer 6b to irradiate the recording and reproducing layer 6c. Accordingly, the light spot is effectively micronized, and information is recorded and reproduced at a recording density below the optical resolution.

85. 发明专利

JPH05325200A OUT-OF-FOCUS DETECTION DEVICE AND OPTICAL HEAD USING IT 失效
公开(公告)号：JPH05325200A
公开(公告)日：1993-12-10
申请号：JP13221192
申请日：1992-05-25
申请人： HITACHI LTD
发明人： NAKAMURA SHIGERU , UMEDA MARIKO
IPC分类号： G11B7/085 , G11B7/09
摘要： PURPOSE:To achieve a focusing operation stably by a method wherein a means which makes the diameter of a subbeam passed through a convergence means smaller than the diameter of a main beam and the linear region of an out-of- focus detection signal, is made wide. CONSTITUTION:A beam from an optical-body laser 11 is set as a main beam via a lens 12. It is separated into a beam of + primary diffraction light 15b and a beam of - primary diffraction light 15c by means of a diffraction grating 14. The astigmatism of a 1/2 wavelength and that of a -1/2 wavelength are given, respectively. The individual beams are transmitted through a beam splitter 16; they are converged by means of a lens 17 (a pupil 18), and a focus 19a is formed. The beams 15b, 15c are focused respectively at points 19b, 19c. The beams are reflected by a pit on an optical disk 20 and condensed by means of a convex lens 22. The individual beams are photodetected by means of photodetectors 23a to 23c; a light-quantity signal 24 is generated. Modulation- factor signals 26b, 26c are output via an envelope detection circuit 25; they are subtracted by means of a differential operation circuit 27; an out-of-focus detection signal 28 is output.

86. 发明专利

JPH0589465A METHOD AND DEVICE FOR OPTICAL INFORMATION RECORDING AND REPRODUCTION 失效
公开(公告)号：JPH0589465A
公开(公告)日：1993-04-09
申请号：JP15848391
申请日：1991-06-28
申请人： HITACHI LTD
发明人： SUKETA YASUSHI , NAKAMURA SHIGERU
IPC分类号： G11B7/00 , G11B7/0045 , G11B7/125 , G11B7/126
摘要： PURPOSE:To suppress a laser noise by pulse-oscillating laser light, and controlling the frequency of a high frequency current in accordance with the length of an optical path between a light emitting point and a recording medium so that reflected return light reaches the laser emitting point within the interruption of the pulse. CONSTITUTION:An optical pickup movable part 11 accesses the recording medium 2 along parallel flux of light from an optical pickup fixing part 10. The position of the movable part 11 is detected by a scale 9, and is inputted to a select circuit 18 as position data 15, and here, the set value data 16 of laser modulation frequency is selected in accordance with the data 15. This is converted into a voltage signal V by a D/A converter 19, and further, into the pulse train of the frequency (f) by a V/f conversion circuit 20. A laser drive circuit 21 generates the pulse current I of the frequency (f), and pulse-drives a semiconductor laser 1. Thus, optimum laser driving corresponding to the position of the movable part 11 can be performed.

87. 发明专利

JPH0567341A OPTICAL HEAD 失效
公开(公告)号：JPH0567341A
公开(公告)日：1993-03-19
申请号：JP4636192
申请日：1992-02-03
申请人： HITACHI LTD
发明人： IMADA RITSUO , ONISHI KUNIKAZU , SASAKI TORU , INOUE MASAYUKI , ARIMOTO AKIRA , NAKAMURA SHIGERU , NAKAO TAKESHI
IPC分类号： G11B7/09 , G11B7/13 , G11B7/135 , G11B11/10 , G11B11/105
摘要： PURPOSE:To provide the optical head by which as for a detection of a focus error signal, a light spot does not cause a misalignment on a photodetector, and also, as for a tracking error signal, its adjustment can be executed, and more-over, which can be used for detecting a signal with regard to a -primary diffracted light, as well. CONSTITUTION:Between a beam splitter 3 and a photodetector 9, a cylindrical lens 7, and a diffraction grating 8 consisting of two areas whose diffraction directions or diffraction angles are different from each other are installed, and a diffracted light of the diffraction grating 8 is guided to the photodetector 9 by containing a O-order diffracted light (direct transmission light). A focus error signal by an astigmatism method is detected by the O-order diffracted light, and a tracking error signal is detected by using a + or - primary diffracted light.

88. 发明专利

JPH0520698A OPTICAL INFORMATION PROCESSOR 失效
公开(公告)号：JPH0520698A
公开(公告)日：1993-01-29
申请号：JP17217491
申请日：1991-07-12
申请人： HITACHI LTD
发明人： UMEDA MARIKO , NAKAMURA SHIGERU
IPC分类号： G02B7/28 , G11B7/09
摘要： PURPOSE:To obtain an out-of-focus detecting system capable of self-adjusting the target of focusing by finding the modulation degree of two input signals modulated with a mark and making this difference signal an out-of focus detecting signal. CONSTITUTION:Reflected beams 10b, 10c by an optical disk 8 are attained to photodetecting elements 11b, 11c, by the elements 11b, 11c, light quantity signals 12b, 12c are outputted. When the disk 8 is moved to the horizontal direction of the paper face, the beams 10b, 10c are modulated by the mark of a pit, etc. The amplitude of the modulation of the signals 12b, 12c are outputted as a modulation degree signals 14b, 14c by that the upper level and the lower level of the amplitude of an inputted signal are detected and the upper level is divided by the lower level in an envelope detecting circuit 13b, 13c. A differential arithmetic circuit 15 is inputted with the signals 14b, 14c, and the difference signal is outputted as the out-of-focus detecting signal 16. Thus, the out-of-focus detecting system generating no offset to the out-of-focus detecting signal even when a part of a luminous flux is erased and capable of self-adjusting the target of focusing.

89. 发明专利

JPH04311828A OPTICAL HEAD AND INFORMATION RECORDING DEVICE 失效
公开(公告)号：JPH04311828A
公开(公告)日：1992-11-04
申请号：JP7756791
申请日：1991-04-10
申请人： HITACHI LTD
发明人： NAKAMURA SHIGERU , ARIMOTO AKIRA , NAKAO TAKESHI , UMEDA MARIKO
IPC分类号： G11B7/12 , G11B7/135 , H01S5/022
摘要： PURPOSE:To obtain a small and integral optical head by closing a semiconductor laser in an optical head case to fix an image forming optical system, a diffraction grating to separate reflecting and incident beam, a beam separating optical system and a photodetector. CONSTITUTION:An optical head includes a semiconductor 1, a diffraction grating plate 2 of a double refraction substance, a lambda/4 plate 5, a focus lens 6, tripartite photodetectors 7A and 7B, a photodetector 8 for the power monitor of the laser 1 and an arithmetic circuit 9 of a photodetector output signal. A diffraction grating 3 is on the surface of the laser 1 side of the plate 2 and a diffraction grating 4 is on the surface of the lens 6 side. An emitting beam 14 from the laser 1 is the grating 4 and separated into main and subbeams 15a and 15b, 15c. The beams 15a-15c are reflected by the optical disk, a reflecting beam 16 to pass through the lambda/4 plate 5 is separated into beams 17A and 17B by the grating 3 and detected by the 3-divided type photodector 7A and 7B. The photodetectors 7A and 7B, the photodetector 8 for power monitor, an electronic circuit 9 are fixed onto a circular substrate 11.

90. 发明专利

JPH03181023A CARRIER AND DEVICE FOR OPTICAL DISK RECORDING AND REPRODUCING 失效
公开(公告)号：JPH03181023A
公开(公告)日：1991-08-07
申请号：JP31875389
申请日：1989-12-11
申请人： HITACHI LTD
发明人： OTAKE MASATOSHI , MITA SEIICHI , NAKAMURA SHIGERU , SUKETA YASUSHI , OBA AKIHIKO
IPC分类号： G11B7/24 , G11B7/00 , G11B7/004 , G11B7/007
摘要： PURPOSE:To regenerate the recording of code data from wobbling data without breaking a pregroup by interruptedly recording wobbling in accordance with truth/falsehood of preliminarily recorded code data. CONSTITUTION:Wobbling of the pregroup is interruptedly recorded with frequency components exceeding the servo band of tracking in accordance with truth/falsehood of code data preliminarily recorded on an optical disk recording and reproducing carrier. That is, tracking guide grooves 2-1 to 2-3 are minutely displaced in the radial direction of the disk with a period higher than a frequency, which has not an influence upon tracking, when the code of data only for read is '1' (true), and a preformat is recorded to prevent wobbling when this code is '0' (false). Thus, data only for reproducing is recorded with the preformat without breaking tracking guide grooves 2-1 to 2-3.

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