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71 条记录 (耗时 0.012 秒)

    Focus error detection system for an optical head
    32.
    发明公开
    Focus error detection system for an optical head 失效
    用于光学头的聚焦误差检测系统

    公开(公告)号：EP0829857A3

    公开(公告)日：2000-01-12

    申请号：EP97115455.4

    申请日：1997-09-05

    申请人： NEC CORPORATION

    发明人： Yamanaka, Yutaka

    IPC分类号： G11B7/09 ,  G11B7/135 ,  G11B7/13

    CPC分类号： G11B7/131 ,  G11B7/0908 ,  G11B7/0912 ,  G11B7/0916 ,  G11B7/094 ,  G11B7/0943 ,  G11B7/1356

    摘要： A focus error detection system in an optical head has an optical divider for dividing an optical beam reflected from an optical disk, and first and second light receiving areas on a photodetector for receiving the split optical beam. Each of the first and second light receiving areas has first and second light receiving sections divided by a boundary which receives one of the split optical beams at the center thereof. Both the difference signals obtained by subtracting the output of the first light receiving section from the output of the second light receiving section of the first and second light receiving areas are respectively normalized by summed signals obtained by adding the outputs of the first and second light receiving sections of the first and second light receiving areas. Both the normalized difference signals are added to obtain a focus error signal for a focus control of the optical head.

    Optical head
    33.
    发明公开
    Optical head 失效

    公开(公告)号：EP0829862A3

    公开(公告)日：1998-07-22

    申请号：EP97115922.3

    申请日：1997-09-12

    申请人： NEC CORPORATION

    发明人： Yamanaka, Yutaka

    IPC分类号： G11B7/12 ,  G11B7/135

    CPC分类号： G11B7/1353 ,  G11B7/0948 ,  G11B7/1275 ,  G11B7/13925 ,  G11B2007/0006 ,  G11B2007/13727

    摘要： The configuration of an optical head is such that it enables movement of and setting of the position of a laser light source along an optical axis to either a first position which corresponds to the position for which an objective lens is designed to accommodate an optical disc having a first substrate thickness, and a third position which is between the first position and a second position at which the aberration with respect to an optical disc having a second substrate thickness, which is different than that of the first optical disc, is minimum. By establishing this third position as a position at which not only is there a reduction in aberration with respect to the second optical disc, but also at which there is no significant reduction in the allowable amount of lateral skew of the laser light source from the optical axis, it is possible to prevent a significant worsening of aberration characteristics, even if the laser light source is skewed from the optical axis.

    Optical head
    34.
    发明公开
    Optical head 失效
    光学头

    公开(公告)号：EP0829862A2

    公开(公告)日：1998-03-18

    申请号：EP97115922.3

    申请日：1997-09-12

    申请人： NEC CORPORATION

    发明人： Yamanaka, Yutaka

    IPC分类号： G11B7/12 ,  G11B7/135

    CPC分类号： G11B7/1353 ,  G11B7/0948 ,  G11B7/1275 ,  G11B7/13925 ,  G11B2007/0006 ,  G11B2007/13727

    摘要： The configuration of an optical head is such that it enables movement of and setting of the position of a laser light source along an optical axis to either a first position which corresponds to the position for which an objective lens is designed to accommodate an optical disc having a first substrate thickness, and a third position which is between the first position and a second position at which the aberration with respect to an optical disc having a second substrate thickness, which is different than that of the first optical disc, is minimum. By establishing this third position as a position at which not only is there a reduction in aberration with respect to the second optical disc, but also at which there is no significant reduction in the allowable amount of lateral skew of the laser light source from the optical axis, it is possible to prevent a significant worsening of aberration characteristics, even if the laser light source is skewed from the optical axis.

    摘要翻译： 光学头的结构是这样的，即它能使激光光源的位置沿光轴移动和设定到第一位置，该第一位置对应于物镜被设计成容纳光盘的位置，该光盘具有 第一基板厚度以及位于第一位置和第二位置之间的第三位置，在所述第二位置处，相对于具有与第一光盘不同的第二基板厚度的光盘的像差最小。 通过将该第三位置设置为不仅相对于第二光盘的像差减少的位置，而且不会使激光光源的横向歪斜容许量从光学上显着降低 即使激光光源从光轴偏斜，也可以防止像差特性的显着恶化。

    Signal reproducing apparatus for optical recording and reproducing equipment and method for the same
    37.
    发明公开
    Signal reproducing apparatus for optical recording and reproducing equipment and method for the same 失效
    用于光学记录和再现设备的信号再现装置及其相关方法

    公开(公告)号：EP0393719A3

    公开(公告)日：1992-01-15

    申请号：EP90107616.6

    申请日：1990-04-23

    申请人： NEC CORPORATION

    发明人： Hirose, Yutaka ,  Yamanaka, Yutaka ,  Okanoue, Kazuhiro

    IPC分类号： G11B7/00

    CPC分类号： G11B7/13 ,  G11B7/005 ,  G11B7/14 ,  G11B11/10515 ,  G11B11/10543 ,  G11B11/10595

    摘要： The apparatus and method is used for recording optical information on an optical disk and reproducing the optical information therefrom by the use of an optical beam. The system is especially adapted to eliminate crosstalk from nearby tracks even when the position of the beam spot fluctuates with respect to a desired track and even when the size of a beam spot incident to the desired track is varied. The apparatus particularly comprises a frequency characteristic converter which receives output signals from a photodetector array (11). The photodetector array (11), for example, comprises 3 photodetectors (100, 101, 102) receiving input beams (130, 131 and 132). The photodetector (100) is associated with a desired track for reproducing a signal, whereas photodetectors (101, 102) are associated with neighbouring tracks for reproducing a replica of crosstalk. The frequency characteristic convertor (12) further comprises transversal filter means (110, 111, 112), each capable of controlling a frequency characteristic, an adder (120), a reference signal generator (121), an error detector (122), a filter control circuit (123) for controlling the filters (110, 111, 112), a timing control circuit (124), a decision circuit (125), a switch (126) and an output terminal (133). The output of the photodetector (100) adapted to reproduce a signal is fed to the timing control circuit (124), which detects the beginning of a preamble signal written in the track beforehand and delivers a control signal to the reference signal generator (121) and switch (126). When the timing control circuit (124) detects the end of the preamble signal, it delivers a control signal to the reference signal generator (121) and switch (126). The characteristic control for the transversal filters (110, 111, 112) is sequentially performed on the basis of the preamble signal and the corresponding reference signal and on the basis of an input signal and an output signal of the decision circuit (125).