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31. 发明专利

JPH11203684A OPTICAL DISK DEVICE 失效
公开(公告)号：JPH11203684A
公开(公告)日：1999-07-30
申请号：JP630398
申请日：1998-01-16
申请人： HITACHI LTD
发明人： KITADA YASUO , KAMISADA TOSHIMASA , SUMIDA MAMORU , YAMAZAKI SHIGEKI
IPC分类号： G11B33/14 , G11B7/085 , G11B19/04
摘要： PROBLEM TO BE SOLVED: To prevent it that the operation of a two-dimensional actuator becomes insperative because foreign matters are stucked and adhered in the gap between a shaft guiding a lens holder freely in a focusing direction and a tracking direction by moving the lens holder while driving the two-dimensional actuator with a prescribed time interval whilst a power source is supplied to this optical disk device. SOLUTION: A lens holder 102 holding the objective lens 101 of a two- diementional actuator has coils 103,104 for drives of a focusing direction and a tracking direction and is engaged with a shaft 106 with a pipe 105 fixed to the holder. When foreign matters are stuck in the gap between the shaft 106 and the pipe 105 and the foreign matters are closely adhered to them in the gap while the shaft 106 and the pipe 105 are not operated for a longtime, the foreign matters generate adhesion and the two-dimensional actuator becomes inoperative. Then, when the device is in an electric conduction state, the obstacle of adhesion is avoided by driving the lens holder 102 while making driving currents to flow through the coils 13, 14 with a prescribed time interval.

32. 发明专利

JPH10222855A OPTICAL HEAD 失效
公开(公告)号：JPH10222855A
公开(公告)日：1998-08-21
申请号：JP2479497
申请日：1997-02-07
申请人： HITACHI LTD
发明人： KITADA YASUO
IPC分类号： G11B7/09
摘要： PROBLEM TO BE SOLVED: To reduce a track offset by preventing a part in which 0-order, +1st- order and -1st-order of diffracted light being main causes increasing the track offset caused in an old generational recording medium set on an optical disk device are overlapped from detecting as a track servo signal. SOLUTION: Whether or not a diffracted light pattern on a photodetector is provided with the part 203 in which the 0-order, +1st-order and -1st-order of the diffracted light are overlapped is judged based on the generational information of the recording medium, and switches 121, 122 are opened/closed by a switch control part 126, and when the part 203 that the 0-order, +1st-order and -1st-order of the diffracted light are overlapped doesn't exist, the light on the photodetector is used as the track servo signal as much as possible, and when the part 203 in which the 0-order, +1st-order and -1st-order of the diffracted light are overlapped exists, by opening the switches 121, 122 so as not to use the light of the part as the track servo signal, the track offset is made hardly to be caused even when the photodetector and the light pattern are position deviated mutually.

33. 发明专利

JPH09282702A OPTICAL HEAD 失效
公开(公告)号：JPH09282702A
公开(公告)日：1997-10-31
申请号：JP8664496
申请日：1996-04-09
申请人： HITACHI LTD
发明人： KAMISADA TOSHIMASA , INOUE MASAYUKI , SASAKI TORU , KITADA YASUO , FUKUI MASAKAZU , KONISHI YOSHIRO
IPC分类号： G11B11/10 , G11B7/09 , G11B7/135 , G11B11/105
摘要： PROBLEM TO BE SOLVED: To simplify an information signal reproducing system and a servo signal detecting system by integration and to detect a tracking error signal with good accuracy. SOLUTION: The laser beam separated by a beam splitter 25 is introduced through an optical system consisting of a Wollaston prism 26 and a diffraction grating 27 to photodetector 28. The two luminous fluxes among the three luminous fluxes separated by the Wollaston prism 26 are further separated by the diffraction grating 27. Information signals are reproduced by using the separated zero order diffracted light and ± first order diffracted light. The other one luminous flux is further separated by the diffraction grating and the focus error signal is detected by using the separated zero order diffracted light. The tracking error signal is detected by using the separated ± first order diffracted light. The photodetecting surface of the photodetector 28 is made smaller by setting the angle formed by the gratings of the diffraction grating 27 smaller than 45 deg. from the dividing line.

34. 发明专利

JPH06168474A OPTICAL HEAD 失效
公开(公告)号：JPH06168474A
公开(公告)日：1994-06-14
申请号：JP31975092
申请日：1992-11-30
申请人： HITACHI LTD
发明人： KITADA YASUO
IPC分类号： G11B7/00 , G11B7/0045 , G11B7/125
摘要： PURPOSE:To provide a detecting constitution without being affected by the wavelength fluctuation of a laser and returned light from a disk in the photodetector for laser power control of an optical head used for an optical disk device. CONSTITUTION:A laser power is monitored by means of a photodetector 11b receiving the peripheral part of a light transmitted from the front end surface of a laser chip 11a inside a laser diode 11 and is controlled. Since a light quantity incident on a collimator lens and a light quantity received by the photodetector are not affected by the wavelength fluctuation of the laser and the returned light from the disk and always keep a constant ratio, stabilized power control is enabled.

35. 发明专利

JPH06162551A OPTICAL HEAD 失效
公开(公告)号：JPH06162551A
公开(公告)日：1994-06-10
申请号：JP30515492
申请日：1992-11-16
申请人： HITACHI LTD
发明人： KONISHI YOSHIRO , KITADA YASUO , KAMISADA TOSHIMASA
IPC分类号： G02B27/09 , G02B27/00 , G11B7/125 , G11B7/135
摘要： PURPOSE:To eliminate the change in a light emitting mode or noise caused by the return light by arranging a prism so that light flux is not made vertically incident on an incident plane. CONSTITUTION:Light flux 1 made incident from a collimator lens 10 is made incident on a prism 2 at an angle theta1. When the incident light flux goes out from the prism 2, it has an angle of theta2 to the prism 2. Light reflected on a prism incident surface 3 is inclined at the angle DELTAtheta1 to the incident light. Similarly, the light flux to be reflected on a prism emitting plane 4 is inclined at an angle of DELTAtheta2 to the incident light. The prism 2 is arranged so that angles DELTAtheta1 and DELTAtheta2 not converge on a laser diode element 8 or a monitor element 9. Thus, since the reflected light flux is not converged to the collimator lens 10, the effect caused by the reflected light from the prism 2 on the laser is excluded.

36. 发明专利

JPH0447534A EXCHANGE METHOD FOR LENS COVER IN OPTICAL RECORDING/ REPRODUCING DEVICE 失效
公开(公告)号：JPH0447534A
公开(公告)日：1992-02-17
申请号：JP15513990
申请日：1990-06-15
申请人： HITACHI LTD
发明人： KAMISADA TOSHIMASA , KITADA YASUO
IPC分类号： G11B23/00 , G11B7/12 , G11B7/121
摘要： PURPOSE:To prevent dust attached on an objective lens by providing a loadable/ unloadable light transmission member which covers the objective lens at the light emitting port of an optical head, and exchanging the member by using a jig for exchange. CONSTITUTION:The light transmission member 18 is fixed on a cover 15 with an adhesive, etc., and the cover 15 is mounted on the case of the optical head 1 removably by a groove 17. A new cover 15' is pressed by moving the tip 29 of a lever 23 which slides the knob 26 of the jig for exchange along an L-groove 25 in a direction of arrow A, and the new cover 15' is moved on a first arm 21, then, presses the cover 15 mounted on the optical head 1. The cover 15 is moved along the groove 17, and is housed in a second arm 30, and the cover 15' is moved along the groove 17 as pressing the cover 15, and is loaded on the optical head 1. Thereby, it is possible to easily exchange the light transmission member 8, and to surely prevent a fault due to the dust attached on the objective lens occurring.

37. 发明专利

JPS63222331A OPTICAL DISK RECORDING AND REPRODUCING DEVICE 失效
公开(公告)号：JPS63222331A
公开(公告)日：1988-09-16
申请号：JP5400987
申请日：1987-03-11
申请人： HITACHI LTD
发明人： KITADA YASUO , WATANABE MASATERU
IPC分类号： G11B7/09
摘要： PURPOSE:To record and reproduce information on both faces of an optical disk without reversing the disk by switching the optical disk set to a table to forward rotation and reverse rotation and focusing the light from an optical head on an arbitrary recording and reproducing face. CONSTITUTION:If the recording or reproducing address on an optical disk 8 accessed by a higher device is placed on a first face 3a of the optical disk 8, a control part 10 controls a driving part to rotate the optical disk in the forward rotation direction by a prescribed number of rotations and controls a focusing part 9 to focus an emitted light 7 from an optical head 5 on a recording part 1a. If the accessed address is placed on a second face 3b, the control part 10 controls the driving part to rotate the optical disk in the reverse rotation direction by a prescribed number of rotations and controls the focusing part 9 to focus an emitted light 6 from the optical head 5 on a recording part 1b.

38. 发明专利

JPS61230633A FOCUS POSITION DETECTING DEVICE 失效
公开(公告)号：JPS61230633A
公开(公告)日：1986-10-14
申请号：JP7092385
申请日：1985-04-05
申请人： HITACHI LTD
发明人： SAITO AKIRA , KAMISADA TOSHIMASA , KITADA YASUO
IPC分类号： G02B7/28 , G11B7/09
摘要： PURPOSE:To obtain a focus position detecting signal which has reduced effects of the position shift of the detection light and the track data signal, by extracting the differential signal of the detected light quantity of a two-split photodetector after the signal passed through a beam splitter having the dependence of incident angle and then extracting only the angle change of the detection light. CONSTITUTION:A beam splitter 30 having no change of the output light intensity to the change of an incident angle is set between a beam splitter 20 whose output light quantity has the dependence of incident angle and a stop-down lens 17. At the same time, a photodetector 31 having the same form as a photodetector 21 is set so that the distance from the lens 17 is equal to the distance between the lens 17 and the detector 21. Then the differential output of the detector 31 is obtained by a subtractor 32, and the differential output is obtained by subtractor 33 to a subtractor 22. Thus a detecting signal 28 obtains the difference of detector outputs between the plus and minus sides of the incident angle of the detection light after subtracting the light intensity of the same areas of both detectors 21 and 31. Thus it is possible to extract only the change of light quantity on the detector 21 due to the change of the focus point.

39. 发明专利

JP2003173552A OPTICAL HEAD AND DISK DEVICE USING THE SAME 审中-公开
公开(公告)号：JP2003173552A
公开(公告)日：2003-06-20
申请号：JP2001372680
申请日：2001-12-06
申请人： HITACHI LTD
发明人： KITADA YASUO , ICHIKAWA KOJI
IPC分类号： G11B7/09
摘要： PROBLEM TO BE SOLVED: To prevent a plastic deformation of an elastic member for supporting an objective lens holder due to an impact force generated at an accidental falling or the like and to assure a necessary moving distance of an objective lens holder. SOLUTION: A plurality of limiting means 41 for limiting the movement of the objective lens holder 2 by an abut of opposite front end faces are provided corresponding to linear elastic members 3 for supporting the objective lens holder, either one or the both of respective opposite end faces of the limiting means 41 have a parabolic external form or one similar to a parabola, and the gap between the both end faces is set smaller than a critical displacement with which the elastic member receives a buckling. COPYRIGHT: (C)2003,JPO

40. 发明专利

JP2000036121A OPTICAL HEAD 失效
公开(公告)号：JP2000036121A
公开(公告)日：2000-02-02
申请号：JP20292798
申请日：1998-07-17
申请人： HITACHI LTD
发明人： KITADA YASUO , KAMISADA TOSHIMASA
IPC分类号： G11B7/09 , G11B7/135
摘要： PROBLEM TO BE SOLVED: To detect focusing error detection signals employing a single photodetector by forming optical spots at the front and the back of a focus on the photodetector and arranging the light receiving surfaces of the photodetector at the positions corresponding to the spots. SOLUTION: The polarization direction of light beams, which are made incident on a polarizing beam splitter 104, is rotated by approximately 90 deg. with respect to the forward light path direction by passing through a 1/4 wavelength plate 105 twice, and the beams are reflected by a polarization beam splitter 104, converged by a detection lens 109, passed through an optical path difference generating plate 110 and made incident on a photodetector 111. The photodetector 111 detects the focusing error detection signal, a track error detection signal, and data signals. The plate 110 is divided into two regions at an approximate center. The thicknesses of the respective regions are made different so that the optical distances of the passing light beams are made different by the different thicknesses and optical path difference is generated. The light receiving surface of the photodetector 111 is arranged to be located at the approximate center of the two focal distances of the luminous fluxes that are divided into two by the plate 110.

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