WO2000070617A1 - An optical storage medium - Google Patents

An optical storage medium Download PDF

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Publication number
WO2000070617A1
WO2000070617A1 PCT/IB2000/000614 IB0000614W WO0070617A1 WO 2000070617 A1 WO2000070617 A1 WO 2000070617A1 IB 0000614 W IB0000614 W IB 0000614W WO 0070617 A1 WO0070617 A1 WO 0070617A1
Authority
WO
WIPO (PCT)
Prior art keywords
disc
filling material
damaged
optical disc
polishing
Prior art date
Application number
PCT/IB2000/000614
Other languages
French (fr)
Inventor
Jurie Mathee
Casper Mathee
Original Assignee
Jurie Mathee
Casper Mathee
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jurie Mathee, Casper Mathee filed Critical Jurie Mathee
Priority to AU43090/00A priority Critical patent/AU4309000A/en
Publication of WO2000070617A1 publication Critical patent/WO2000070617A1/en

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/50—Reconditioning of record carriers; Cleaning of record carriers ; Carrying-off electrostatic charges
    • G11B23/505—Reconditioning of record carriers; Cleaning of record carriers ; Carrying-off electrostatic charges of disk carriers

Definitions

  • THIS INVENTION relates to an optical storage medium. More particularly, this invention relates to a method of repairing a damaged optical disc and to an optical disc.
  • This invention has particular application to an optical disc known as a compact disc or CD, which is used to record sound. It will however be appreciated that this invention equally applies to any type of optical electronic storage medium that uses low-power laser beams to record and retrieve data, such as a compact disc read-only memory or "CD-ROM”, which can store text images as well as sound, a digital versatile disc or digital video disc or “DVD” or playstation disc, which can store sound and video images, a write-once read-many or "WORM” disc, which can be written once and read any number of times, and a disc that is totally rewritable.
  • CD-ROM compact disc read-only memory
  • WORM write-once read-many
  • the data on an optical storage disc is conventionally stored in the form of tiny pits separated by lands and arranged in a spiral pattern on a polycarbonate data layer.
  • the disc is then exposed to vaporised aluminium or silver and sealed with an acrylic outer sealing layer.
  • damaged disc refers to an optical disc which has a damaged surface, i.e. a surface which has been physically damaged by scratching, burning, or the like, so that a cavity and/or protrusion is formed on its surface which, in use, interferes with, or affects the intensity or quality of light reflected from the data layer to a photodiode array.
  • a method of repairing a damaged optical disc including the step of smoothing a damaged surface of the disc.
  • the surface will be the surface of that side of the disc onto which the laser beam of, for example, a CD or DVD player is directed during use.
  • This side is referred to as the reading side of the disc.
  • An optical disc is made largely of a polycarbonate plastic on one side of which the pits and lands are arranged. This side is coated with a layer of aluminium which is covered by a protective acrylic layer. The label of the disc is attached to the acrylic layer.
  • a laser beam is directed through the opposite side of the polycarbonate layer and is reflected by the lands or scattered by the pits and a photodiode array detects the variation in the intensity of the reflected and scattered laser beam.
  • the reading surface will thus be the polycarbonate surface of the operatively lower side of the optical disc.
  • the method may include the step of filling a cavity in the damaged surface with a filling material.
  • the method includes the step of inserting a filling material in a cavity in the surface prior to smoothing the surface.
  • the filling material may be in the form of a spreadable material which is applied as a coating layer to the surface, thereby also filling in any cavities.
  • the surface may then be polished to smooth it.
  • the method may include the step of softening the spreadable material by heating the spreadable material.
  • the surface may be polished by rotating the disc at a high speed relative to a non-static friction pad, or by rotating the disc and the friction pad relative to one another or by rotating the friction pad relative to a stationary disc so that heat generated between the upper surface and the pad raises the temperature of the filling material until it is at least partially fluid and spreadable.
  • the non-static friction pad prevents a static charge build-up and thereby minimizes dust attraction.
  • heating the spreadable material may be brought about by polishing the surface by means of a polishing or friction pad and allowing heat generated between the surface and the polishing or friction pad during the polishing step to heat the spreadable material.
  • the filling material may include a polymeric or plastics substance or a mixture of polymeric and plastics substances. It may be a synthetic polymeric substance.
  • the material may be VONAX (trade name) which is supplied by E S Mowat and Sons (Pty) Ltd. VONAX is described as a glossing composition for plastics and is provided in the form of a soap-like bar. It is also available as a liquid.
  • the filling material may include a lubricant.
  • the lubricant may be selected from silicones and fats.
  • the method may include the step of identifying a region of the disc which has been damaged.
  • Smoothing the surface of the disc may include the step of melting or softening at least a portion of the surface in order to smooth it.
  • the surface may be melted or softened by means of at least one laser beam.
  • the thermoplastic nature of polycarbonate allows reversible softening or melting of the surface to occur.
  • the region may thus be subjected to laser treatment, thereby raising the temperature of the surface so that it softens or melts and is levelled.
  • the laser treatment may include subjecting the disc to a plurality of laser beams which simultaneously impinge on the surface.
  • the identifying step may include manually or visually identifying the damaged region or positioning the disc in a computing means in which the disc is scanned by optical means in order to identify the damaged region.
  • the optical disc may be brought into contact with, and displaced relative to, a friction pad so that frictional heat is generated and the method may include allowing the frictional heat to melt or soften the portion of the surface to smooth it.
  • the heat generated by friction between the disc and the friction pad was sufficient to cause softening or melting of the top approximately 35 - 40 ⁇ of the damaged surface of the disc.
  • the pressure of the friction pad on the surface will preferably be arranged to bring about uniform softening or melting of a portion of the surface.
  • the optical disc may be brought into contact with and displaced relative to a friction pad so that frictional heat is generated and the method may then include the step of applying a filling material to the surface of the disc and allowing the frictional heat to melt or soften a portion of the surface so that the melted or softened portion combines with the filling material to smooth the surface.
  • the filling material may be VONAX (trade name) . Naturally, any suitable material which will combine with the melted or softened portion of the surface of the disc will be suitable.
  • the filling material may be combined with a lubricant.
  • the lubricant may be as hereinbefore described.
  • the method includes the step of skimming off or abrading at least a part of the surface of the disc by a polishing or glossing process thereby smoothing the surface.
  • smoothing the surface of the disc may include the step of removing a portion of the surface.
  • a coating layer may be applied to the surface if the amount of material removed exceeds a predetermined level.
  • the portion of the surface may be skimmed off by laser treatment or by abrading, polishing or glossing. It will be appreciated that the surface may be removed up to a position adjacent the data level in which the pits and lands are located without damaging the data on the disc.
  • the portion of the surface of the disc may be removed by a process selected from laser treatment, abrading, polishing or glossing.
  • the portion may be removed by glossing using VONAX (trade name) as hereinbefore described.
  • the method may also include a first step of cleaning the surface in order to remove dust particles from the surface and in particular from any scratches or cavities.
  • the surface is cleaned by an alcohol, such as surgical spirits, or the like.
  • a damaged compact disc which was scratched was repaired in accordance with the method of the invention.
  • the damaged surface of the disc was first cleaned with surgical spirit in order to remove dust particles from the surface and in particular from the scratches.
  • Other suitable solvents or cleaning liquids can instead be used.
  • the cleaning process is important to the quality of the repair because dust particles remain in the scratches, these can become trapped in the repaired surface during the repairing process. This, in turn, can later cause problems with data retrieval from the disc.
  • the compact disc was then secured to a rubber-coated rotatable surface by means of a rubber nut and a plastics glossing composition in the form of VONAX (trade name) was applied to a pair of buffing pads positioned above the surface of the compact disc.
  • the disc was then rotated in an anti-clockwise direction and the buffing pads in a clockwise direction and the pads were brought into contact with the surface of the compact disc.
  • the buffing pads were rotated at a minimum rate of about 2 800 rpm but preferably at a rate of 3 500 - 700 rpm and the compact disc was rotated at a rate which was sufficient to ensure an even buffing and heat distribution over the surface of the disc. During this process the scratches were removed.
  • composition was in the form of "Liquid Tripoly No 8" which is also available from E S Mowat and Sons
  • the buffing pads were then removed, the disc was mounted on a turntable and the compact disc was again cleaned (using Savlon for example) and micro-dust particles were blown from the surface with an airstream.
  • the compact disc whilst still warm was then rotated in an anti-clockwise direction on a turntable and an anti-static cloth was drawn outwardly from the centre of the rotating disc to create micro grooves in the still warm surface in a spiral pattern. These grooves provide a path along which dust particles can move or be displaced when the compact disc is rotated in use and the laser source moves over the surface of the disc. This serves to prevent future dust damage of the disc and is an important additional feature of the invention.
  • the compact disc was then removed, and dried in a current of air. The disc was then tested for satisfactory performance. If necessary the method of the invention may be repeated.
  • spiral micro-grooves which allow dust to be ejected from the surface during use is also a useful advantage of the invention.
  • the Applicant has successfully used the method of the invention to repair more than 8700 compact discs, digital video discs and the like on a commercial basis.

Landscapes

  • Manufacturing Optical Record Carriers (AREA)

Abstract

A method of repairing a damaged optical disc includes the step of smoothing a damaged surface of the disc. The smoothing is achieved by filling a cavity in the damaged surface with a filling material, melting or softening a portion of the surface by heating it or by glossing the surface.

Description

AN OPTICAL STORAGE MEDIUM
THIS INVENTION relates to an optical storage medium. More particularly, this invention relates to a method of repairing a damaged optical disc and to an optical disc.
This invention has particular application to an optical disc known as a compact disc or CD, which is used to record sound. It will however be appreciated that this invention equally applies to any type of optical electronic storage medium that uses low-power laser beams to record and retrieve data, such as a compact disc read-only memory or "CD-ROM", which can store text images as well as sound, a digital versatile disc or digital video disc or "DVD" or playstation disc, which can store sound and video images, a write-once read-many or "WORM" disc, which can be written once and read any number of times, and a disc that is totally rewritable.
The data on an optical storage disc is conventionally stored in the form of tiny pits separated by lands and arranged in a spiral pattern on a polycarbonate data layer. The disc is then exposed to vaporised aluminium or silver and sealed with an acrylic outer sealing layer.
In this specification, unless the context clearly indicates the contrary, the term "damaged disc" refers to an optical disc which has a damaged surface, i.e. a surface which has been physically damaged by scratching, burning, or the like, so that a cavity and/or protrusion is formed on its surface which, in use, interferes with, or affects the intensity or quality of light reflected from the data layer to a photodiode array.
According to a first aspect of the invention, there is provided a method of repairing a damaged optical disc, the method including the step of smoothing a damaged surface of the disc.
The surface will be the surface of that side of the disc onto which the laser beam of, for example, a CD or DVD player is directed during use. This side is referred to as the reading side of the disc. An optical disc is made largely of a polycarbonate plastic on one side of which the pits and lands are arranged. This side is coated with a layer of aluminium which is covered by a protective acrylic layer. The label of the disc is attached to the acrylic layer. A laser beam is directed through the opposite side of the polycarbonate layer and is reflected by the lands or scattered by the pits and a photodiode array detects the variation in the intensity of the reflected and scattered laser beam. The reading surface will thus be the polycarbonate surface of the operatively lower side of the optical disc.
The method may include the step of filling a cavity in the damaged surface with a filling material.
Thus, in one embodiment of the invention, the method includes the step of inserting a filling material in a cavity in the surface prior to smoothing the surface. The filling material may be in the form of a spreadable material which is applied as a coating layer to the surface, thereby also filling in any cavities. The surface may then be polished to smooth it. The method may include the step of softening the spreadable material by heating the spreadable material.
For, example, the surface may be polished by rotating the disc at a high speed relative to a non-static friction pad, or by rotating the disc and the friction pad relative to one another or by rotating the friction pad relative to a stationary disc so that heat generated between the upper surface and the pad raises the temperature of the filling material until it is at least partially fluid and spreadable. The non-static friction pad prevents a static charge build-up and thereby minimizes dust attraction.
Thus, heating the spreadable material may be brought about by polishing the surface by means of a polishing or friction pad and allowing heat generated between the surface and the polishing or friction pad during the polishing step to heat the spreadable material. The filling material may include a polymeric or plastics substance or a mixture of polymeric and plastics substances. It may be a synthetic polymeric substance. The material may be VONAX (trade name) which is supplied by E S Mowat and Sons (Pty) Ltd. VONAX is described as a glossing composition for plastics and is provided in the form of a soap-like bar. It is also available as a liquid.
The filling material may include a lubricant. The lubricant may be selected from silicones and fats. The method may include the step of identifying a region of the disc which has been damaged.
Smoothing the surface of the disc may include the step of melting or softening at least a portion of the surface in order to smooth it. The surface may be melted or softened by means of at least one laser beam. The thermoplastic nature of polycarbonate allows reversible softening or melting of the surface to occur.
The region may thus be subjected to laser treatment, thereby raising the temperature of the surface so that it softens or melts and is levelled. The laser treatment may include subjecting the disc to a plurality of laser beams which simultaneously impinge on the surface.
The identifying step may include manually or visually identifying the damaged region or positioning the disc in a computing means in which the disc is scanned by optical means in order to identify the damaged region.
Instead, the optical disc may be brought into contact with, and displaced relative to, a friction pad so that frictional heat is generated and the method may include allowing the frictional heat to melt or soften the portion of the surface to smooth it.
The heat generated by friction between the disc and the friction pad was sufficient to cause softening or melting of the top approximately 35 - 40 μ of the damaged surface of the disc. The pressure of the friction pad on the surface will preferably be arranged to bring about uniform softening or melting of a portion of the surface. In another embodiment of the invention the optical disc may be brought into contact with and displaced relative to a friction pad so that frictional heat is generated and the method may then include the step of applying a filling material to the surface of the disc and allowing the frictional heat to melt or soften a portion of the surface so that the melted or softened portion combines with the filling material to smooth the surface.
The filling material may be VONAX (trade name) . Naturally, any suitable material which will combine with the melted or softened portion of the surface of the disc will be suitable. The filling material may be combined with a lubricant. The lubricant may be as hereinbefore described.
In yet a further embodiment of the invention, the method includes the step of skimming off or abrading at least a part of the surface of the disc by a polishing or glossing process thereby smoothing the surface. Thus, smoothing the surface of the disc may include the step of removing a portion of the surface. In this case, a coating layer may be applied to the surface if the amount of material removed exceeds a predetermined level. The portion of the surface may be skimmed off by laser treatment or by abrading, polishing or glossing. It will be appreciated that the surface may be removed up to a position adjacent the data level in which the pits and lands are located without damaging the data on the disc.
Thus, the portion of the surface of the disc may be removed by a process selected from laser treatment, abrading, polishing or glossing. The portion may be removed by glossing using VONAX (trade name) as hereinbefore described.
The method may also include a first step of cleaning the surface in order to remove dust particles from the surface and in particular from any scratches or cavities. In a preferred embodiment of the invention, the surface is cleaned by an alcohol, such as surgical spirits, or the like.
According to a second aspect of the invention, there is provided a compact disc which has been repaired by a method as described above.
The invention is now described, by way of example.
A damaged compact disc which was scratched was repaired in accordance with the method of the invention.
The damaged surface of the disc was first cleaned with surgical spirit in order to remove dust particles from the surface and in particular from the scratches. Other suitable solvents or cleaning liquids can instead be used. The cleaning process is important to the quality of the repair because dust particles remain in the scratches, these can become trapped in the repaired surface during the repairing process. This, in turn, can later cause problems with data retrieval from the disc.
The compact disc was then secured to a rubber-coated rotatable surface by means of a rubber nut and a plastics glossing composition in the form of VONAX (trade name) was applied to a pair of buffing pads positioned above the surface of the compact disc. The disc was then rotated in an anti-clockwise direction and the buffing pads in a clockwise direction and the pads were brought into contact with the surface of the compact disc. The buffing pads were rotated at a minimum rate of about 2 800 rpm but preferably at a rate of 3 500 - 700 rpm and the compact disc was rotated at a rate which was sufficient to ensure an even buffing and heat distribution over the surface of the disc. During this process the scratches were removed.
In another embodiment, the composition was in the form of "Liquid Tripoly No 8" which is also available from E S Mowat and Sons
(Pty) Ltd.
The buffing pads were then removed, the disc was mounted on a turntable and the compact disc was again cleaned (using Savlon for example) and micro-dust particles were blown from the surface with an airstream.
The compact disc whilst still warm was then rotated in an anti-clockwise direction on a turntable and an anti-static cloth was drawn outwardly from the centre of the rotating disc to create micro grooves in the still warm surface in a spiral pattern. These grooves provide a path along which dust particles can move or be displaced when the compact disc is rotated in use and the laser source moves over the surface of the disc. This serves to prevent future dust damage of the disc and is an important additional feature of the invention. The compact disc was then removed, and dried in a current of air. The disc was then tested for satisfactory performance. If necessary the method of the invention may be repeated.
It is an advantage of the invention illustrated that it provides a simple and inexpensive way to repair a damaged optical disc. Without being bound thereby, the Applicant believes that the heating of the damaged surface of the disc to its melting or softening point together with the buffing process results in flow of the partially melted or softened surface which closes scratches, cavities and the like in the surface without significant (or any) loss of material. The Applicant also believes that the filler material, which is also heated during the buffing process, combines with or mixes with the partially melted or softened polycarbonate material from which the compact disc is made during the process.
The spiral micro-grooves which allow dust to be ejected from the surface during use is also a useful advantage of the invention.
The Applicant has successfully used the method of the invention to repair more than 8700 compact discs, digital video discs and the like on a commercial basis.

Claims

CLAIMS:
1 . A method of repairing a damaged optical disc, the method
including the step of smoothing a damaged surface of the disc.
2. A method as claimed in Claim 1 , which includes the step of
filling a cavity in the damaged surface with a filling material.
3. A method as claimed in Claim 2, in which the filling material
is a spreadable material.
4. A method as claimed in Claim 3, which includes the step of
softening the spreadable material by heating the spreadable material.
5. A method as claimed in Claim 4, in which heating the
spreadable material is brought about by polishing the surface by means
of a polishing pad and allowing heat generated between the surface and
the polishing pad during the polishing step to heat the spreadable
material.
6. A method as claimed in any one of Claims 2 - 5 inclusive,
in which the filling material includes a polymeric substance.
7. A method as claimed in Claim 6, in which the filling material
is VONAX (trade name) .
8. A method as claimed in Claim 7, in which the filling material
includes a lubricant.
9. A method as claimed in Claim 8, in which the lubricant is
selected from silicones and fats.
1 0. A method as claimed in Claim 1 , in which smoothing the
damaged surface of the disc includes the step of melting or softening at
least a portion of the surface in order to smooth it.
1 1 . A method as claimed in Claim 10, in which the surface is
softened or melted by means of at least one laser beam.
1 2. A method as claimed in Claim 1 0, in which the optical disc
is brought into contact with, and displaced relative to, a friction pad so
that frictional heat is generated and which includes allowing the frictional
heat to melt or soften the portion of the surface to smooth it.
1 3. A method as claimed in Claim 1 , in which the optical disc
is brought into contact with and displaced relative to a friction pad so
that frictional heat is generated and which includes the step of applying
a filling material to the surface of the surface of the disc and allowing the
frictional heat to melt or soften a portion of the surface so that the
melted or softened portion combines with the filling material to smooth
the surface.
14. A method as claimed in Claim 1 3, in which the filling
material is VONAX (trade name) .
1 5. A method as claimed in Claim 1 3 or Claim 1 4, in which the
filling material is combined with a lubricant.
1 6. A method as claimed in Claim 1 , in which smoothing the
surface of the disc includes the step of removing a portion of the
surface.
1 7. A method as claimed in Claim 1 2, in which the portion of
the surface of the disc is removed by a process selected from laser
treatment, abrading, polishing and glossing.
1 8. A method as claimed in Claim 1 3, which includes the
subsequent step of applying a coating layer to the disc.
1 9. A method as claimed in Claim 1 , in which the optical disc
is brought into contact with and displaced relative to a glossing pad to
which has been added a glossing composition to smooth the damaged
surface of the disc.
20. A method as claimed in Claim 1 5, in which the glossing
composition is selected from VONAX (trade name) and liquid Tripoly No.
8 (trade name) .
21 . An optical disc which has been repaired by a method as
claimed in any one of the preceding claims.
22. A method of repairing a damaged optical disc as claimed in
Claim 1 , substantially as herein described and illustrated.
23. A method of repairing a damaged optical disc, substantially
as herein described.
24. An optical disc as claimed in Claim 1 5, substantially as
herein described and illustrated.
25. An optical disc substantially as herein described.
PCT/IB2000/000614 1999-05-14 2000-05-10 An optical storage medium WO2000070617A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU43090/00A AU4309000A (en) 1999-05-14 2000-05-10 An optical storage medium

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA993343 1999-05-14
ZA99/3343 1999-05-14

Publications (1)

Publication Number Publication Date
WO2000070617A1 true WO2000070617A1 (en) 2000-11-23

Family

ID=25587731

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2000/000614 WO2000070617A1 (en) 1999-05-14 2000-05-10 An optical storage medium

Country Status (2)

Country Link
AU (1) AU4309000A (en)
WO (1) WO2000070617A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2290655A1 (en) * 2009-08-26 2011-03-02 Harald Schmid Method for repairing digital recording media

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995021890A1 (en) * 1994-02-09 1995-08-17 Boca Chemicals International Disc repair system
JPH0945048A (en) * 1995-07-31 1997-02-14 Sony Corp Recovering method for optical disk
US5733179A (en) * 1995-04-03 1998-03-31 Bauer; Jason Method and apparatus for reconditioning digital recording discs
JPH1092148A (en) * 1996-09-16 1998-04-10 Kanami Seto Apparatus for restoration of flaw on compact disk for music
JPH10302442A (en) * 1997-04-22 1998-11-13 Matsushita Electric Ind Co Ltd Optical disk restoration device
JPH1131373A (en) * 1997-07-10 1999-02-02 Matsushita Electric Ind Co Ltd Optical disk restoring device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995021890A1 (en) * 1994-02-09 1995-08-17 Boca Chemicals International Disc repair system
US5733179A (en) * 1995-04-03 1998-03-31 Bauer; Jason Method and apparatus for reconditioning digital recording discs
JPH0945048A (en) * 1995-07-31 1997-02-14 Sony Corp Recovering method for optical disk
JPH1092148A (en) * 1996-09-16 1998-04-10 Kanami Seto Apparatus for restoration of flaw on compact disk for music
JPH10302442A (en) * 1997-04-22 1998-11-13 Matsushita Electric Ind Co Ltd Optical disk restoration device
JPH1131373A (en) * 1997-07-10 1999-02-02 Matsushita Electric Ind Co Ltd Optical disk restoring device

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1997, no. 06 30 June 1997 (1997-06-30) *
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 09 31 July 1998 (1998-07-31) *
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 02 26 February 1999 (1999-02-26) *
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 05 31 May 1999 (1999-05-31) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2290655A1 (en) * 2009-08-26 2011-03-02 Harald Schmid Method for repairing digital recording media

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