Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
  • G11B7/0045—Recording
  • G11B7/00452—Recording involving bubble or bump forming
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/2403—Layers; Shape, structure or physical properties thereof
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
  • G11B7/24085—Pits
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
  • G11B2007/24302—Metals or metalloids
  • G11B2007/24304—Metals or metalloids group 2 or 12 elements (e.g. Be, Ca, Mg, Zn, Cd)
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
  • G11B2007/24302—Metals or metalloids
  • G11B2007/24316—Metals or metalloids group 16 elements (i.e. chalcogenides, Se, Te)
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
  • G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
  • G11B7/2533—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins
  • G11B7/2534—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins polycarbonates [PC]

Definitions

• An irreversible optical recording medium comprising a track with raised low relief areas and a method of using such a medium.
• the invention relates to an irreversible optical recording medium comprising at least one substrate on which is arranged at least one photosensitive layer comprising a structured front face intended to receive optical radiation during recording and / or reading data operations, with a track with raised areas.
• the invention also relates to a method of using said support.
• Optical recording for example on CD-R type media (recordable compact disc also known as “Compact Disc Recordable”) and DVD-R (recordable multi-purpose digital disc also known as Anglo-Saxon) "Digital Versatile Disc Recordable”), is most often achieved through a layer of coloring material deposited on a plastic substrate and covered by a reflective metal layer.
• irreversible optical recording technologies in materials dye, sometimes have high manufacturing costs, especially in relation to the price of dyes and the cost of labor for dye handling steps.
• writable optical media erasable or not, a groove in the form of a spiral, materialized by a raised track on the surface of the substrate, allows accurate writing and reading of the data thanks to a focusing servo system.
• the pitch of the track is usually defined by the international specification of disc format. For example, DVDs have a track pitch of 740nm while optical discs using a blue laser, better known as a "Blu-Ray" disc have a track pitch of 320nm.
• the track is also characterized by the depth and width of the furrow.
• irreversible recording media that is to say non-erasable, based on the use of dyes, require the realization of a deep groove, for example 140 to 180nm for a DVD-R type disk .
• This high groove depth implies a relatively high substrate pressing time.
• the longer the pressing time of the substrate the greater the total duration of the manufacturing cycle of a support increases and the manufacturing efficiency of the supports decreases, which increases the cost of manufacture.
• Inorganic materials may have an advantage in terms of production cost and performance over organic dyes.
• the size of the marks is not compatible with the required storage density, in particular, because of the presence of a bead of material around the marks.
• the aim of the invention is an irreversible optical recording medium which overcomes the drawbacks of the prior art and, more particularly, having a relatively low manufacturing cost and a high manufacturing efficiency, compared to the supports according to the prior art. .
• the support is characterized in that the raised areas have:
• the invention also aims a method of using such a medium overcomes the disadvantages of the prior art. According to the invention, this object is achieved by the fact that the raised areas having:
• a height substantially between a minimum value varying substantially linearly, decreasingly, from 25 nm to 32 nm, and a maximum value of 35 nm, for relief zone widths between 200 nm and 250 nm, recording and reading of the data are located at the level of the relief zones.
• Figure 1 is a schematic representation, in section, of a track disposed on the front face of a substrate and having two raised areas.
• FIG. 2 schematically represents, in section, a support comprising the track according to FIG.
• FIG. 3 represents a reflectivity value of the order of 60% and standardized push-pull signal values of the order of 0.30 and 0.60, depending on the height and width of the areas in relief of a track.
• An irreversible optical recording medium preferably in the form of an optical disk or a smart card, comprises at least one substrate on which at least one photosensitive layer is arranged.
• the photosensitive layer has a structured front face for receiving optical radiation during recording and / or reading operations.
• the irreversible optical recording medium may also comprise one or more additional layers disposed between the substrate and the photosensitive layer and / or on the front face of the photosensitive layer.
• the photosensitive layer preferably comprises an inorganic material capable of being deformed locally under the action of optical radiation.
• the photosensitive layer also provides sufficient reflection and partial absorption of light from the optical radiation.
• the energy absorbed by the photosensitive layer induces a local heating in the layer which causes a local deformation thereof.
• the local deformation may be in the form of a bubble or in the form of a hole and is a mark in the photosensitive layer.
• the marks of the photosensitive layer being less reflective than the undistorted areas of the layer, it is then possible to read the support by detecting the marks formed.
• the length of the marks and the spaces between them make it possible to encode information. It is also possible to vary the length of the marks, by applying a specific modulation of the power of the applied optical radiation, said specific modulation of the power corresponding to a write strategy.
• the shape of the marks is determined by the type of materials in the photosensitive layer.
• hole-forming materials such as tellurium-antimony or selenium-based materials, have been described in an article by M. Terao et al. ("Chalcogenide Thin Films for Laser-beam Recordings by Thermal Creation of Holes", J. Appl Phys 50 (41), November 1979, 6881-6886).
• M. Terao et al. Chocogenide Thin Films for Laser-beam Recordings by Thermal Creation of Holes
• Such materials generally have a relatively high melting point and include at least one element that is easy to vaporize.
• the composition of the photosensitive layer material is generally adapted to ensure a bubble forming quality compatible with a good standard deviation of the mark lengths (Jitter) written on the disk.
• the photosensitive layer may comprise an alloy of zinc tellurium (Zn-Te), zinc selenide (ZnSe), phosphate and zinc (PZn), arsenic and zinc (AsZn) or of cadmium telluride (CdTe).
• Zn-Te zinc tellurium
• ZnSe zinc selenide
• PZn phosphate and zinc
• AsZn arsenic and zinc
• CdTe cadmium telluride
• the most suitable proportion is 65 atomic% of zinc for 35 atomic% of tellurium and the thickness of the layer is preferably between 15 and 50 nm, and preferably equal to 40 nm.
• FIG. 1 shows, in a conventional manner, a substrate 1 having a free rear face 1a and a structured front face 1b forming a track having raised areas 1c, the assembly forms, preferably a spiral.
• the front face 1b has two raised areas 1c, schematically shown in a trapezoidal shape.
• the optical radiation (s) enabling the writing and / or reading of the data come from the face free rear 1a of the substrate 1. They then pass through said substrate and focus locally at a groove. Said groove, known according to the prior art and seen from the free rear face 1 a, then corresponds to all of the raised areas 1 c described in Figure 1.
• the width L and the height H of a zone in relief 1 c according to the invention correspond substantially to the depth and width of a groove of an optical recording medium according to the prior art.
• the raised areas 1c have a height H of substantially between 25 nm and 35 nm, for widths L of relief zones 1c of between 250 nm and 370 nm.
• their height H lies between a minimum value varying substantially linearly, decreasingly, from 25 nm to 32 nm, and a maximum value substantially of 35 nm.
• the relief zones 1c preferably have a maximum height H max of 30 nm and a maximum width L max of 370 nm.
• the width L of a relief zone is preferably defined as the width recognized by the servo system. Such a width generally corresponds to the interface between the substrate and the photosensitive layer. Schematically, in FIG. 1, the width L of a relief zone 1c corresponds to the smallest of the two bases of the trapezium representing said zone while the height H corresponds to the height of said trapezium.
• an irreversible optical recording medium comprises the substrate 1 as represented in FIG. 1.
• a photosensitive layer 2 is deposited on the structured front face 1b of the substrate 1, preferably in a uniform way.
• the front face 2a of the photosensitive layer 2 is then structured, so that it comprises regions in relief, on which are preferably located the recording and reading of the data. So the layer photosensitive deforms locally at the level of the raised regions, disposed above the raised areas 1 c of the front face of the substrate.
• a reflecting layer 3 preferably having a thickness greater than or equal to 15 nanometers, is preferably disposed on the front face 2a of the photosensitive layer 2.
• the reflecting layer is disposed between the photosensitive layer 2 and a protective layer 4
• Optical radiation 5 is intended to allow the recording and / or reading of the data. It is preferably a focused and power-modulated laser beam, reaching a raised region of the photosensitive layer 2, disposed under a raised area 1c of the track, after having passed through the protective support 4 and the reflective layer 3. .
• the reflective layer 3 is intended to improve the optical properties of the photosensitive layer 2 and is more particularly suitable when the photosensitive layer 2 is poorly reflective in a predetermined wavelength range.
• the reflective layer 3 is, for example, adapted to a photosensitive layer of zinc tellurium with a wavelength range of optical radiation between 630nm and 650nm.
• the reflective layer 3 also makes it possible to improve the thermal behavior of the photosensitive layer 2. It may consist of silver, gold, aluminum or copper.
• the photosensitive layer 2 for example made of zinc tellurium and intended to be deformed locally under the action of optical radiation 5, has a thickness of between 20 nm and 30 nm and comprises a front face 2 a through which the optical radiation 5 is received, through the reflective layer 3.
• the two layers, photosensitive 2 and reflecting 3, form an inorganic stack capable of obtaining a strong initial reflection while maintaining a good writing sensitivity and a good contrast.
• the thickness of the inorganic stack is substantially equal to the height of the raised areas 1c of the track.
• the irreversible optical recording medium is not limited to the embodiment described above.
• the reflective layer 3 may be replaced by a deformable layer, transparent to optical radiation and non-birefringent, as described in International Application No. PCT / FR04 / 01897 filed on 16/07/2004, under priority of a French patent application No. FR0308875 filed on 21/07/2003.
• the deformable layer is then disposed between the photosensitive layer and the protective support. Thus, the deformable layer is traversed by the optical radiation before it reaches the structured front face of the photosensitive layer.
• the deformable layer preferably has a thickness less than or equal to 200 ⁇ m, and more particularly between 2 ⁇ m and 100 ⁇ m. It preferably comprises a polymer previously crosslinked by light radiation, such as polymers chosen from silicones or flexible polymers of acrylic base.
• the deformable layer is a layer capable of following the deformations of the photosensitive layer during the writing operations on the photosensitive layer.
• the optical write radiation passes through both the deformable layer and at least a portion of the photosensitive layer, which allows to create deformations in the deformable layer adding to the reliefs created in the photosensitive layer.
• Having a deformable layer on the front face of the photosensitive layer promotes, in particular, the creation of precise marks in the photosensitive layer. Indeed, when the photosensitive layer is deformed, the deformable layer has a deformation of the same type, accompanying the deformation of the photosensitive layer.
• the deformable layer allows, thus, to limit the enlargement of the writing marks of, in particular, the diffusion of the heat of the optical radiation during the writing. The deformable layer thus makes it possible to obtain better quality marks.
• a metal layer preferably having a thickness less than or equal to 15 nm can be arranged between the photosensitive layer and the deformable layer, to improve the reflection of the photosensitive layer.
• a protective layer against oxidation, transparent and very thin can also be disposed between said metal layer and the deformable layer.
• the recording medium may also comprise an additional semi-transparent photosensitive layer, possibly with an additional transparent deformable layer.
• the substrate and the protective layer used for an irreversible optical recording medium are preferably made of plastic, for example polycarbonate (PC) or polymethyl methacrylate (PMMA) and they are made by molding.
• the thickness of the substrates as well as the pitch of the track are variable, according to the specifications imposed by the type of recording medium desired. For example, for a DVD or for an HD-DVD (High Definition DVD also known as the "High Definition-DVD"), the substrate has a thickness of 0.6 mm while to achieve a disc "Blu-Ray", the thickness of the substrate is 1, 1 mm.
• the pitch of the substrate track is 0, 74 ⁇ m for DVDs and 0.32 ⁇ m for "Blu-Ray DVD” or HD-DVD.
• the protective layer is non-birefringent and preferably comprises front and rear planar faces. Its thickness is determined by the type of media format you want. Thus, for a DVD, the sum of the thicknesses of the protective layer and the layers disposed between the protective layer and the substrate must be of the order of 0.6mm, whereas for a "Blu-Ray DVD" disc, the sum of the thicknesses must be of the order of 100 ⁇ m.
• the height H and the width L of the relief zones are advantageously chosen so as to retain:
• the reflectivity of the recording disk, before and after writing must be between 45% and 85% while the standardized "push-pull" signal makes it possible to measure the ease with which a recording medium to follow the track, must be between 0.30 and 0.60.
• the curves A and B respectively represent standardized push-pull signal values of 0.30 and 0.60, depending on the height and the width of the raised zones while the layer C represents a reflectivity value equal to 45%.
• the recording medium is situated in a rectangular zone I comprised between the curves. A and C.
• the support has a reflectivity greater than or equal to 45% (curve C) and the standard "push-pull" signal is between 0.30 and 0.60.
• the recording medium also meets the specifications of ECMA 349 in terms of reflectivity and tracking.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Optical Record Carriers And Manufacture Thereof (AREA)

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• 2005
  • 2005-01-27 FR FR0500863A patent/FR2881262B1/fr not_active Expired - Fee Related
• 2006
  • 2006-01-25 EP EP06709167A patent/EP1842187A1/fr not_active Withdrawn
  • 2006-01-25 KR KR1020077017526A patent/KR20070116788A/ko not_active Application Discontinuation
  • 2006-01-25 WO PCT/FR2006/000169 patent/WO2006079716A1/fr active Application Filing
  • 2006-01-25 US US11/794,666 patent/US20080260983A1/en not_active Abandoned
  • 2006-01-25 CN CNA2006800033244A patent/CN101124629A/zh active Pending
  • 2006-01-25 JP JP2007552677A patent/JP2008529198A/ja active Pending

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