EP0072704A2
Expired / Lapsed
EP
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Method and apparatus for optically recording and reproducing information
Assignee: Panasonic Holdings Corp
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Filing: 1982-08-18
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Granted: —
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Expires: 2002-08-18
Abstract
Abstract 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.
Inventors
- 👤 Isao Satoh
- 👤 Tomio Yoshida
- 👤 Shunji Ohara
- 👤 Kenji Koishi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 17:03
CPC Classifications
G; G11; G11B; G11B17/00; G11B17/005; G11B27/00; G11B27/02; G11B27/031; G11B27/034; G11B27/036; G11B27/10; G11B27/11; G11B27/19; G11B27/24; G11B27/28; G11B27/32; G11B27/327; G11B27/329; G11B2220/00; G11B2220/20; G11B2220/21; G11B2220/215; G11B2220/216; G11B2220/218; G11B2220/60; G11B2220/65
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
197 words
Apparatus for optically recording and reproducing information comprising: (a) first means for driving an optical disc; (b) second means for emitting laser light beam so that the beam is incident on said disc; (c) third means for modulating said laser light beam in accordance with an information signal; (d) fourth means for driving said second means; (e) fifth means for controlling said first to fourth means so that information is written on a file region on said optical disc, while directory of said region is also written in a directory region; (f) sixth means for generating a superposing writing signal; (g) seventh means for modulating said laser light beam by said superposing writing signal; (h) eighth means responsive to light reflected at said disc; and (i) ninth means for detecting a region on which said laser light beam modulated by said superposing writing signal has been irradiated from the output signal from said eighth means; said fifth means being responsive to an output signal from said eighth means so that region or regions, on which said laser light beam modualted by said superposing writing signal has been irradiated, are skipped when reproducing information from said optical disc.
Claim 2
Dependent Claim
197 words
Apparatus for optically recording and reproducing information comprising: (a) first means for driving an optical disc; (b) second means for emitting laser light beam so that the beam is incident on said disc; (c) third means for modulating said laser light beam in accordance with an information signal; (d) fourth means for driving said second means; (e) fifth means for controlling said first to fourth means so that information is written on a file region on said optical disc, while directory of said region is also written in a directory region; (f) sixth means for generating a superposing writing signal; (g) seventh means for modulating said laser light beam by said superposing writing signal; (h) eighth means responsive to light reflected at said disc; and (i) ninth means for detecting a region on which said laser light beam modulated by said superposing writing signal has been irradiated from the output signal from said eighth means; said fifth means being responsive to an output signal from said eighth means so that region or regions, on which said laser light beam modualted by said superposing writing signal has been irradiated, are skipped when reproducing information from said optical disc.
Claim 3
Dependent Claim
27 words
Apparatus as claimed in Claim 1, wherein said ninth means comprises an envelope detecting circuit which detects the envelope of the output signal from said seventh means.
Claim 4
Dependent Claim
125 words
Apparatus as claimed in Claim 2, wherein said envelope detecting circuit comprises: . (a) a high pass filter responsive to the output signal from said eighth means; (b) a clamping circuit responsive to the output signal from said high pass filter; (c) an envelope detector responsive to the output signal from said clamping circuit; (d) a comparator responsive to the output signal from said envelope detector and to a reference voltage; (e) a clock pulse generator; (f) a couter arranged to count the number of said clock pulses in response to the output signal of said comparator; (g) a latch arranged to latch the count of said counter and to reset the latched count to zero in response to the output signal from said comparator.
Claim 5
Dependent Claim
66 words
Apparatus as claimed in any one of Claims 1 to 4, further comprising: (a) a memory for temporarily storing the directory of information to be renewed, said directory being read out from said directory region of said optical disc; (b) means for changing the directory stored in said memory; (k) means for writing the changed directory on said directory region, at the end of prewritten directories.
Claim 6
Dependent Claim
43 words
Apparatus as claimed in any one of Claims 1 to 4, wherein said sixth means comprises a d.c. signal generator so that said laser light beam is modulated to have a constant intensity for superposing writing with which prewritten information is substantially erased.
Claim 7
Dependent Claim
91 words
Apparatus as claimed in any one of Claims 1 to 4, wherein said sixth means comprises an a.c. signal generator so that said laser light beam is modulated in such a manner that the length of a pit made on said disc by irradiating said laser light beam modulated by said superposing writing signal is greater than the twice the shortest pit made by said laser light beam modulated by said information signal so that prewritten information is substantially erased by said laser light beam modulated by said superposing writing signal.
Claim 8
Independent Claim
173 words
A method of renewing information prewritten on an optical disc having a file region and a directory region, comprising the steps of: (a) searching directory of a designated data to be renewed; (b) reading out said data to renew the same; (c) storing said directory in a memory; (d) erasing said data prewritten on said disc by superposing writing which is effected by irradiating a laser light beam on a corresponsing region on said file region, where said laser light beam is modulated by a predetermined d.c. or a.c. signal; (e) searching the last position of data prewritten on said disc; (f) writing the renewed data in an unused region which follows said last position; (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written; (h) searching the last position of directories which are prewritten in said directory region; and (i) writing said new directory at an unsued region in said directory region which follows said last position of directories.
Claim 9
Independent Claim
173 words
A method of renewing information prewritten on an optical disc having a file region and a directory region, comprising the steps of: (a) searching directory of a designated data to be renewed; (b) reading out said data to renew the same; (c) storing said directory in a memory; (d) erasing said data prewritten on said disc by superposing writing which is effected by irradiating a laser light beam on a corresponsing region on said file region, where said laser light beam is modulated by a predetermined d.c. or a.c. signal; (e) searching the last position of data prewritten on said disc; (f) writing the renewed data in an unused region which follows said last position; (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written; (h) searching the last position of directories which are prewritten in said directory region; and (i) writing said new directory at an unsued region in said directory region which follows said last position of directories.
Claim 10
Independent Claim
173 words
A method of renewing information prewritten on an optical disc having a file region and a directory region, comprising the steps of: (a) searching directory of a designated data to be renewed; (b) reading out said data to renew the same; (c) storing said directory in a memory; (d) erasing said directory prewritten on said disc by superposing writing which is effected by irradiating a laser light beam on a corresponsing region in said directory region, where said laser light beam is modulated by a predetermined d.c. or a.c. signal; (e) searching the last position of data prewritten on said disc; (f). writing the renewed data in an unused region which follows said last position; (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written; (h) searching the last position of directories which are prewritten in said directory region; and (i) writing said new directory at an unsued region in said directory region which follows said last position of directories.
Claim 11
Independent Claim
173 words
A method of renewing information prewritten on an optical disc having a file region and a directory region, comprising the steps of: (a) searching directory of a designated data to be renewed; (b) reading out said data to renew the same; (c) storing said directory in a memory; (d) erasing said directory prewritten on said disc by superposing writing which is effected by irradiating a laser light beam on a corresponsing region in said directory region, where said laser light beam is modulated by a predetermined d.c. or a.c. signal; (e) searching the last position of data prewritten on said disc; (f). writing the renewed data in an unused region which follows said last position; (g) renewing the directory stored in said memory so that a new directory designates the position where said renewed data has been written; (h) searching the last position of directories which are prewritten in said directory region; and (i) writing said new directory at an unsued region in said directory region which follows said last position of directories.
Claim 12
Independent Claim
76 words
A method of reading out infomation prewritten on an optical disc having a file region and a directory region, comprising the steps of: (d) detecting a reproduced signal to check the envelope thereof so that it can be ascertained whether information in each region can be read out or not; and (e) reading out information from each region by skipping one or more regions when it has been detected that information therein cannot be read out.
Claim 13
Independent Claim
76 words
A method of reading out infomation prewritten on an optical disc having a file region and a directory region, comprising the steps of: (d) detecting a reproduced signal to check the envelope thereof so that it can be ascertained whether information in each region can be read out or not; and (e) reading out information from each region by skipping one or more regions when it has been detected that information therein cannot be read out.
References Cited (Backward Citations)
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