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91.发明公开
公开(公告)号：EP0072704A3
公开(公告)日：1984-06-06
申请号：EP82304360
申请日：1982-08-18
发明人： Satoh, Isao , Yoshida, Tomio , Ohara, Shunji , Koishi, Kenji
CPC分类号： G11B17/005 , G11B27/034 , G11B27/036 , G11B27/11 , G11B27/19 , G11B27/24 , G11B27/329 , G11B2220/20 , G11B2220/216 , G11B2220/218 , G11B2220/65
摘要： In an optical disc (1) having a file region (31) and a directory region (30) for carrying various pieces of information or data, one or more designated information can be erased by irradiating a laser light beam on a corresponding region in the file region where the light beam is modulated by a superposing writing signal which may be a d.c. or a predetermined a.c. signal. When it is intended to renew the information, designated information is first read out and stored in an external memory prior to performing superposing writing. Meanwhile, the data is renewed and is then written on an unused region in the file region. The directory of the renewed data region is also written so that the renewed information will be read out by searching the new directory. In another embodiment of the invention, the . information in the file region is not erased to renew the same, but its directory is erased by superposing writing. A new directory for a renewed information, which is written in unused region in the same manner as the above, is written so that the renewed information can be read out by using the new directory. When reproducing, an envelope of the reproduced signal is detected to see whether information can be read out or not. Thus, erased information is skipped to reproduce only unerased information.
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公开(公告)号：EP0082357A1
公开(公告)日：1983-06-29
申请号：EP82111047.5
申请日：1982-11-30
发明人： Ohara, Shunji , Yoshida, Tomio , Satoh, Isao , Koishi, Kenji
CPC分类号： G11B7/126 , H01S5/06832
摘要： A system for driving a semiconductor laser which is especially adapted for use with an optical recording and reproducing device is disclosed. In the write mode the power of laser light emitted from the semiconductor laser is so raised above a threshold or critical level that the laser beam focused on the surface of a recording medium can cause physical, chemical or electromagnetical changes thereof, but in the readout or reproduction mode, the power of laser light is lowered than the threshold or critical level and focused on the recording medium. A laser light power control loop is provided which is enabled or energized only in the readout or reproduction mode, so that the laser light can be maintained at a predetermined level. On the other hand, this control loop is disabled in the write or recording mode so that a predetermined value of current is superposed on the readout current sampled and held immediately the write or recording mode is initiated and the current thus superposed upon each other flows into the semiconductor laser, whereby the power of laser light can be rapidly raised from the readout or reproducing laser light power to the write or recording laser light power.
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93.发明公开
公开(公告)号：EP0072704A2
公开(公告)日：1983-02-23
申请号：EP82304360.9
申请日：1982-08-18
发明人： Satoh, Isao , Yoshida, Tomio , Ohara, Shunji , Koishi, Kenji
CPC分类号： G11B17/005 , G11B27/034 , G11B27/036 , G11B27/11 , G11B27/19 , G11B27/24 , G11B27/329 , G11B2220/20 , G11B2220/216 , G11B2220/218 , G11B2220/65
摘要： In an optical disc (1) having a file region (31) and a directory region (30) for carrying various pieces of information or data, one or more designated information can be erased by irradiating a laser light beam on a corresponding region in the file region where the light beam is modulated by a superposing writing signal which may be a d.c. or a predetermined a.c. signal. When it is intended to renew the information, designated information is first read out and stored in an external memory prior to performing superposing writing. Meanwhile, the data is renewed and is then written on an unused region in the file region. The directory of the renewed data region is also written so that the renewed information will be read out by searching the new directory. In another embodiment of the invention, the . information in the file region is not erased to renew the same, but its directory is erased by superposing writing. A new directory for a renewed information, which is written in unused region in the same manner as the above, is written so that the renewed information can be read out by using the new directory. When reproducing, an envelope of the reproduced signal is detected to see whether information can be read out or not. Thus, erased information is skipped to reproduce only unerased information.
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