CA1124396A - Method of manufacturing an optically readable information disk - Google Patents
Method of manufacturing an optically readable information diskInfo
- Publication number
- CA1124396A CA1124396A CA311,349A CA311349A CA1124396A CA 1124396 A CA1124396 A CA 1124396A CA 311349 A CA311349 A CA 311349A CA 1124396 A CA1124396 A CA 1124396A
- Authority
- CA
- Canada
- Prior art keywords
- optical structure
- plate
- information
- radiation
- information carrier
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
Links
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
- G11B7/24—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
- G11B7/254—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 protective topcoat 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
- G11B7/241—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
- G11B7/257—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 layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording 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
- G11B7/252—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
- G11B7/254—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 protective topcoat layers
- G11B2007/25408—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 protective topcoat layers consisting essentially of inorganic materials
- G11B2007/25414—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 protective topcoat layers consisting essentially of inorganic materials containing Group 13 elements (B, Al, Ga)
-
- 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
- G11B7/256—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 layers improving adhesion between 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
- G11B7/241—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
- G11B7/258—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 reflective layers
- G11B7/2585—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 reflective layers based on aluminium
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
- Manufacturing Optical Record Carriers (AREA)
Abstract
PHN.8897 ABSTRACT:
The invention relates to a method of manufac-turing optically readable information disks, in which a transparent plastics information carrier comprising a radiation-reflecting optical structure on one side, is provided with a flat, stiffening, heat-conducting plate which is connected throughout its surface to the radiation-reflecting optical structure of the information carrier by means of an adhesive.
The invention relates to a method of manufac-turing optically readable information disks, in which a transparent plastics information carrier comprising a radiation-reflecting optical structure on one side, is provided with a flat, stiffening, heat-conducting plate which is connected throughout its surface to the radiation-reflecting optical structure of the information carrier by means of an adhesive.
Description
~24396 The invention relates to a method of manufact-uring an optically readable information disk, in which a transparent plastics information carrier comprising a radiation-reflecting optical structure on one side is provided, on the side of the optical structure, with a cover plate connected thereto by means of an adhes-iv~ .
Such a method is known from Netherlands PatentApplication 72 ll 999 in the name of Applicants laid open to public inspection on March 5, 1974.
The disadvantage of the known method is that there is a real chance that the optically readable information disks manufactured according to the method : will show defects or deviations in the optical struc-ture in the long run, so that the quality of the stored information, for example, video information or audio information, is reduced.
A11 the optical readable information disks manufactured so far from a plastic synthetic resin have the above disadvantage. It has therefore been ~ endeavoured to improve this, special search having :~ been made for special compositions of synthetic resins showing the desired great stability for longer periods r P~-TN.8897 112439~;
of time and in varying cllmatological conditions. In this connection it is to be noted that very stringent requirements have to be imposed on the stability o~
a plastics information disk in view of the great fine-ness of the information structure. ~s stated also in the above Patent Application, said structure usually consists of radiation-reflecting areas, arranged in tracks, of very small diMensions, in the order of mag-nitude of 1/u. These areas are, for example, small blocks and intermediate areas situated in one plane, the coefficient of reflection of the blocks dif`fering from that of the intermediate areas. The optical struc-ture preferably consists of small blocks and inter-mediate areas having the same coefficients of reflec-tion, the blocks and intermediate areas being situ-ated at different levels Thus a crenellated struc-~ ture of the information track is obtained with a dif-I ference in height between the blocks and the inter-mediate areas of` approximately 0.5/u. The inf`ormation track may be spiral-like or be constructed f`rom con-centric circles.
The radiation-reflectlng optical structure is read in reflection by meaus of a focused light beam, in particular laser light.
Plastics information d:isks having a unilateral reflecting optical structure can be mass-produced while using matrices. Various methods may be used, for example ' ~24396 a pressing process described inter alia in our Canadian Patent 998,173 which issued on October 5, 1976. Another known method is an injection mould-ing process or a moulding process. German Offen-legungsschrift 23 43 020, for example, discloses a moulding process in which a liquid polyurethane resin with a polyester substrate thereon is provided on a matrix of silicone rubber. After curing of the urethane resin, the substrate with the cured poly-urethane layer connected thereto is removed from the matrix surface. Another method of manufacturing is the so-called printing process, in which a thermo-plastic foil is provided with the desired optical structure by a treatment with a rotating matrix which is provided, for example, on a roller.
The resulting information disks are then provided, on the side of the optical structure, with a radiation-reflecting layer, for example, a layer of metal or a layer of a selenide dielectric. A
suitable radiation-reflecting layer is or example, a layer of aluminium,silver or gold provided by vap-our deposition or by electroless plating. In order to protect the radiation-reflecting layer from chem-ical and mechanical attack, a protective layer of plastics is provided hereon. This usually is a layer of lacquer, but according to the above Canadian Patent 998,173, it may alternatively be a thin sheet or foil B
:
l PI-IN.8897 ; I 7-1-1978.
~` .
provided with an adhesive.
Another known method of manufacturing information disks provided unilaterally with a reflecting optical structure starts from a substrate in disk form on which a reflective layer is vapour-deposited via an apertured mask. So in this method no matrix is used.
i Instead Or a vapour deposition process, an etching process rnay a]ternatively be used~ in which a layer of photoresist provided on a metal layer is exposed to light v;a a mask and is developed, after which the exposed parts of the metal layer are etched away.
These latter methods are considered to be less suitable for series manufacture.
- I .
It has also been tried to remove the above dis-advantage of reduction in quality of the-optical struc-- ture by making such improvements in the manufacturing technique that the pressure load and thermal load exerted on the synthetic resin are minimum. It has been suggested, for example~ in the pressing process and the printing process, to heat only the uppermost layer of the synthetio resin in which the in~ormation structure is to be provided.
. IIowever, all these attempts have failed to pro-duce an optimal re~sult. Applicants have invented a method o~ manufacturing optically readable information disks which does not show the above disadvantage.
More in particular the present invention relates .. ,. : .
.
' .' ' ~ . ~ . , : ' .~ . , .
P~IN.8897 7-1-1978.
~lZ43~6 .
,~
to a method of the kind mentioned in the preamble which t is characterized in that the cover plate is a flat~
, stiffening, heat-conducting plate manufac-tured from inorganic material and connected to the information carrier throughout its surface.
~ This characterizing measure in the method accor-1~l ding to the invention is based on the following insight gained by Applicants.
In Applicants' opinion, the reduced quality of the in~ormation disk is mainly the result of micro-¦ structured ~orces, l.e. forces which act on a very small ;t~ surface part of the information disk and which are re-i~ leased upon rs_ading the disk by means of laser light.
j~ The laser light beam focused on-the optical I ::
$ ~ 15 structure of the information disk will traverse the ~ transparent synthetic resin without noteworthy loss `~ of light energy and will then be reflected by the ra-` :
dlation-reflecting layer. Dependent on the coefficient 6~ ~ of reflection of the reflecting layer used, - generally 1~ 20 a metal layer - more or less light energy will be 3~ absorbed by the reflecting layer. The absorbed light .
~ ~ energy is converted into thermal energy; as a result 1 ~ ~
of this the temperature of the layer will rise locally, which in turn produces a local heating of the part of the optical structure engaging the reflecting layer.
Many internal stresses are present in the part of the informatlon carrier comprising the optical structure.
, .' . , .
`~Z4396 In connection herewith it is to be noted that in the above-described manufacture of plastics information carriers which are provided unilaterally with an opt-ical structure, a thermal load and a pressure load are exerted on the thermoplastic material to be pro-cessed. This is the more prominent in a pressing or printing process, in which the optical structure is provided in a heated thermoplastic synthetic resin under pressure and by means of a matrix. Cooling is ~ 10 then carried out, the internal stresses introduced ; into the material under the influence of pressure and heat being frozen-in. Such internal stresses occur frequently in particular in that part of the synthe-tic resin where the deformation is maximum, in other words in or near the optical structure.
Internal stresses are present even in the information carriers manufactured according to methods of manufacturing plastics information carriers in which no elevated pressure or high temperature is used. In this connection, reference is made to our Canadian Patent Application 288,224 which was filed on October 5, 1977. The process described in sald Application starts from a liquid lacquer which can be cured with light, for example U.V.-light and which is spread over the information-carrying surface of a metal matrix. A transparent plastics sheet is then provided over the lacquer, after which the lacquer is B
.
. ~ . ~ - . ` . . . .
'' ! ' ' PHN.8897 10-10-1~77 ~124396 exposed to light via the plastics sheet, cured and finally the assembly of plastics sheet and the infor-mation-carrying cured lacquer layer connected thereto is removed from the matrix surface.
The plastics information carrier thus manufac-tured also shows internal stresses, especially in the plastics sheet which, during the manufacture thereof, for example, by means of an extrusion process, has also been subjected to a pressure and thermal treatment.
As already stated hereinbefore, a very local heating of the plastics information carrier in or near the optical structure takes place when the information disk is exposed to laser light. The heated surface area is very small, in the order of magnitude of 1~ microns. The stresses present in the heated part of the information carrier will be released and the forces resulting herefrom will produce a deformation, however small in dimension. In view of the detail fineness of the optical structure, this results 1n errors in the stored information to be read.
By using a heat-conducting plate according to the present in~en$ion, upon irradiating the optical ~; ; structure with laser light, the energy absorbed by the reflecting Iayer will flow for the greater part to ~ ~ 2~ the heat-conducting plate so that no noteworthy rise of ;~ temperature will occur a-t the area of the irradiated surface. The information carrier and in particular the , ' .
.
' s ~ ` :
PHN.8897 ~Z4396 optical structure thereof will hence not be heated, so that no internal stresses are released.
In addition to the above-described micro-struc-tured ~orces, macro-structured ~orces also occur which are operative over a larger surface of the plastics ~, information carrier. These are in particular forces which, in ~pplicants' opinion, are the result of a uni-lateral absorption or release of moisture by the in-s formation carrier and which result in warping of the information carrier. A comparatively small extent of j warping over a large surface area of the plate will I as a rule not exert a direct influence on the in~ormation -1 to be read, since the objective which focus~s the ¦ laser light can keep the gradually ~arying distance 1~ ~ to the optical structure within the depth of focus which j is a ~èw microns, if desired by a compensating gradual ~ displacement of the objective. In the case in which the :;J
~ carrier warps considerably over a smaller distance, ,~ ~ the objective can no longer follow-the varying position ¦ 20 Or ~the optical structure upon reading and the in~ormation carrier is no longer optically readable.
The flat, stif~ening, heat-conducting plate used ; ~ according to the invention can receive the above-mentioned forces without de~ormation o~ the plate ~5 occurring. An information disk manufactured according to the invention will not warp.
The method according to the invention produces .
_~ _ . . .
., :
.
.~ PIIN,8897 ~ ~.Z43~6 .. .
¦I good results in particular if the flat, stiffening, ¦ heat-conducting plate used is a metal plate or a glass plate in a thickness of 0.2-2 mm. Owing to -s the very good thermal conductivity and in addition the e~cellent thermal capacity~ a plate is to be z preferred which is manufactured from metal, such as nickel,steel or aluminium.
This applies in particular to an aluminium plate in a thickness of 0.3 to 1.3 mm.
In a further favourable embodiment of the method according to the invention the side of the flat plate remote from the information carrier is provided with a second transparent plastics information carrier com-prising a unilateral radiation-reflecting optical struc-- ture, the said side of the flat plate being connected throughout its surface to the radiation-reflecting op-; tical structure of the information carrier by means of an adhesive.
This results in an information disk carrying information on two sides which compri9es the double quantity of information, or~ in other words, has a double playing time. Moreover the further advantage is ob-tained that there is a fair chance that the macro-structured forces which may occur in the information carriers situated on both sides of the flat plate, com~
pensate each other at least partly. In this connection it is noted that life tests under ext:reme atmospheric `` ' P:~IN.88g7 ~L124396 circumstances have demonstra-ted that such an information s carrier remains entirely flat if herein a comparatively thin aluminium plate of 0.5 mm is used.
The adhesive used in the method according to the invention is of a conventional type, for example, a two-components adhesive. In an advantageous embodi-ment a radiation-curable lacquer is used, for example, an ultraviol0t-curable lacquer on the basis of acrylic acid. The thin liquid lacquer can easily be provided on one of the surfaces to be connected, for example by i means of a spraying process or a cen-trifuging process, `l~ that is to say, either on the informa-tion-carrying sur-face of the information carrier, or on the flat, stiffening, heat-conducting plate. A rapid curing of the ;, 15 laquer is possible by exposure via the transparent in-,~ , ~ formation carrier. It has been found that the radiation-Y~ reflecting layer which reflects in particular in the infrared region, still passes sufficient shortwave light, ~`~ for example ultraviolet light.
; ~ 20 ` If desired, the flat, stif~ening, heat-conduc-i~ ~ ting plate used may be provided with reinforcement ribs on the sids remote from the in~ormation carrier. An ; ~ information carrier and a plate may also be used which both have a central aperture so that the resulting ` ~ ~
information disk has a central aperture.
The invention will now be described in greater detail with reference to the drawing, in which: -' ' ~ , -1 1-' ' ' ' .
: . ` ` ' , . Pl-IN.8897 4~9~;
~,' 1 , '` .
Figure 1 is a cross sectional view of a plastics information carrier used in the method5 Figure 2 is a cross-sectional view of an in~or-. mation carrier obtained according to the invention, and Figure 3 is a cross-sectional view of another embodiment of an informatlon disk obtained according to the invention, Reference numeral 1 in Figure 1 denotes a trans-parent plastics information carrier comprising an op-I . tical structure 2 on one side. Information carrier 1 -`i .
~J 10 with optical structure 2 has a thickness of approximate-`. ly 1 mm and is manufactured from transparent polyvinyl chloride/acetate copolymer according to a known pressi.ng .process. The optical structure is crenellated and consists of small blocks 3 with intermediate-areas 4 the dimen-¦~ 15 sions of which lie in the order of magnitude of 1/u.
, ~ Optical structure 2 is covered with a vapour deposited ~J, radiation-reflecting aluminium làyer 5, approximately ~! 300 ~ thick 1 ~ .
~ ~ On the side o~ optical structure 2~ the informa-¦~ 20 tion carrier 1 is provided with a 0.5 mm thick aluminium .~ .plate 6 (Fig~ure 2) while using a layer of adhesive, not ~ : shown, for example, a two-components adhesive.
. <
The resulting information disk is shown in ,~ Figur.e 2. The disk is read optically and in re~lection :. .
¦~ 25 by mean: o~ laser light in the direction denoted by an ~ arrow.
.
Re~erenoe numeral 7 in Figure 3 denotes a 0.5 mm PHN.8897 ~;24396 !
thick aluminium plate provided on both sides with plastics information carriers, referenced 8 and 9, , respectively. Information carr:iers 8 and 9 correspond i to that shown in Figure 1 and are provided on one ' 5 side with an optical structure 10, 11 covered by a vapour-deposited aluminium layer, not shown. Infor-mation carriers 8, 9 are connected to plate 7 on the side o~ the optical strueture 10, 11 by means of an adhesive, not shown. The information disk shown in ~igure 3 is read bilaterally in the direction denoted by arrows.
; The thickness (appro~imately 1 rnm) of the plas-tics information earriers 1(Figures 1, 2) and 8, 9 (~i-~, gure 3) is amply suffieient to keep dust particles or seratches possibly present on the ~surface beyond the ~¦~ depth of focus of the ob~ective, not sho~, which focuses the reading beam on the optical structures 2 igures 1, 2) and 10, 11 (Figure 3~).
~ .
' .
Such a method is known from Netherlands PatentApplication 72 ll 999 in the name of Applicants laid open to public inspection on March 5, 1974.
The disadvantage of the known method is that there is a real chance that the optically readable information disks manufactured according to the method : will show defects or deviations in the optical struc-ture in the long run, so that the quality of the stored information, for example, video information or audio information, is reduced.
A11 the optical readable information disks manufactured so far from a plastic synthetic resin have the above disadvantage. It has therefore been ~ endeavoured to improve this, special search having :~ been made for special compositions of synthetic resins showing the desired great stability for longer periods r P~-TN.8897 112439~;
of time and in varying cllmatological conditions. In this connection it is to be noted that very stringent requirements have to be imposed on the stability o~
a plastics information disk in view of the great fine-ness of the information structure. ~s stated also in the above Patent Application, said structure usually consists of radiation-reflecting areas, arranged in tracks, of very small diMensions, in the order of mag-nitude of 1/u. These areas are, for example, small blocks and intermediate areas situated in one plane, the coefficient of reflection of the blocks dif`fering from that of the intermediate areas. The optical struc-ture preferably consists of small blocks and inter-mediate areas having the same coefficients of reflec-tion, the blocks and intermediate areas being situ-ated at different levels Thus a crenellated struc-~ ture of the information track is obtained with a dif-I ference in height between the blocks and the inter-mediate areas of` approximately 0.5/u. The inf`ormation track may be spiral-like or be constructed f`rom con-centric circles.
The radiation-reflectlng optical structure is read in reflection by meaus of a focused light beam, in particular laser light.
Plastics information d:isks having a unilateral reflecting optical structure can be mass-produced while using matrices. Various methods may be used, for example ' ~24396 a pressing process described inter alia in our Canadian Patent 998,173 which issued on October 5, 1976. Another known method is an injection mould-ing process or a moulding process. German Offen-legungsschrift 23 43 020, for example, discloses a moulding process in which a liquid polyurethane resin with a polyester substrate thereon is provided on a matrix of silicone rubber. After curing of the urethane resin, the substrate with the cured poly-urethane layer connected thereto is removed from the matrix surface. Another method of manufacturing is the so-called printing process, in which a thermo-plastic foil is provided with the desired optical structure by a treatment with a rotating matrix which is provided, for example, on a roller.
The resulting information disks are then provided, on the side of the optical structure, with a radiation-reflecting layer, for example, a layer of metal or a layer of a selenide dielectric. A
suitable radiation-reflecting layer is or example, a layer of aluminium,silver or gold provided by vap-our deposition or by electroless plating. In order to protect the radiation-reflecting layer from chem-ical and mechanical attack, a protective layer of plastics is provided hereon. This usually is a layer of lacquer, but according to the above Canadian Patent 998,173, it may alternatively be a thin sheet or foil B
:
l PI-IN.8897 ; I 7-1-1978.
~` .
provided with an adhesive.
Another known method of manufacturing information disks provided unilaterally with a reflecting optical structure starts from a substrate in disk form on which a reflective layer is vapour-deposited via an apertured mask. So in this method no matrix is used.
i Instead Or a vapour deposition process, an etching process rnay a]ternatively be used~ in which a layer of photoresist provided on a metal layer is exposed to light v;a a mask and is developed, after which the exposed parts of the metal layer are etched away.
These latter methods are considered to be less suitable for series manufacture.
- I .
It has also been tried to remove the above dis-advantage of reduction in quality of the-optical struc-- ture by making such improvements in the manufacturing technique that the pressure load and thermal load exerted on the synthetic resin are minimum. It has been suggested, for example~ in the pressing process and the printing process, to heat only the uppermost layer of the synthetio resin in which the in~ormation structure is to be provided.
. IIowever, all these attempts have failed to pro-duce an optimal re~sult. Applicants have invented a method o~ manufacturing optically readable information disks which does not show the above disadvantage.
More in particular the present invention relates .. ,. : .
.
' .' ' ~ . ~ . , : ' .~ . , .
P~IN.8897 7-1-1978.
~lZ43~6 .
,~
to a method of the kind mentioned in the preamble which t is characterized in that the cover plate is a flat~
, stiffening, heat-conducting plate manufac-tured from inorganic material and connected to the information carrier throughout its surface.
~ This characterizing measure in the method accor-1~l ding to the invention is based on the following insight gained by Applicants.
In Applicants' opinion, the reduced quality of the in~ormation disk is mainly the result of micro-¦ structured ~orces, l.e. forces which act on a very small ;t~ surface part of the information disk and which are re-i~ leased upon rs_ading the disk by means of laser light.
j~ The laser light beam focused on-the optical I ::
$ ~ 15 structure of the information disk will traverse the ~ transparent synthetic resin without noteworthy loss `~ of light energy and will then be reflected by the ra-` :
dlation-reflecting layer. Dependent on the coefficient 6~ ~ of reflection of the reflecting layer used, - generally 1~ 20 a metal layer - more or less light energy will be 3~ absorbed by the reflecting layer. The absorbed light .
~ ~ energy is converted into thermal energy; as a result 1 ~ ~
of this the temperature of the layer will rise locally, which in turn produces a local heating of the part of the optical structure engaging the reflecting layer.
Many internal stresses are present in the part of the informatlon carrier comprising the optical structure.
, .' . , .
`~Z4396 In connection herewith it is to be noted that in the above-described manufacture of plastics information carriers which are provided unilaterally with an opt-ical structure, a thermal load and a pressure load are exerted on the thermoplastic material to be pro-cessed. This is the more prominent in a pressing or printing process, in which the optical structure is provided in a heated thermoplastic synthetic resin under pressure and by means of a matrix. Cooling is ~ 10 then carried out, the internal stresses introduced ; into the material under the influence of pressure and heat being frozen-in. Such internal stresses occur frequently in particular in that part of the synthe-tic resin where the deformation is maximum, in other words in or near the optical structure.
Internal stresses are present even in the information carriers manufactured according to methods of manufacturing plastics information carriers in which no elevated pressure or high temperature is used. In this connection, reference is made to our Canadian Patent Application 288,224 which was filed on October 5, 1977. The process described in sald Application starts from a liquid lacquer which can be cured with light, for example U.V.-light and which is spread over the information-carrying surface of a metal matrix. A transparent plastics sheet is then provided over the lacquer, after which the lacquer is B
.
. ~ . ~ - . ` . . . .
'' ! ' ' PHN.8897 10-10-1~77 ~124396 exposed to light via the plastics sheet, cured and finally the assembly of plastics sheet and the infor-mation-carrying cured lacquer layer connected thereto is removed from the matrix surface.
The plastics information carrier thus manufac-tured also shows internal stresses, especially in the plastics sheet which, during the manufacture thereof, for example, by means of an extrusion process, has also been subjected to a pressure and thermal treatment.
As already stated hereinbefore, a very local heating of the plastics information carrier in or near the optical structure takes place when the information disk is exposed to laser light. The heated surface area is very small, in the order of magnitude of 1~ microns. The stresses present in the heated part of the information carrier will be released and the forces resulting herefrom will produce a deformation, however small in dimension. In view of the detail fineness of the optical structure, this results 1n errors in the stored information to be read.
By using a heat-conducting plate according to the present in~en$ion, upon irradiating the optical ~; ; structure with laser light, the energy absorbed by the reflecting Iayer will flow for the greater part to ~ ~ 2~ the heat-conducting plate so that no noteworthy rise of ;~ temperature will occur a-t the area of the irradiated surface. The information carrier and in particular the , ' .
.
' s ~ ` :
PHN.8897 ~Z4396 optical structure thereof will hence not be heated, so that no internal stresses are released.
In addition to the above-described micro-struc-tured ~orces, macro-structured ~orces also occur which are operative over a larger surface of the plastics ~, information carrier. These are in particular forces which, in ~pplicants' opinion, are the result of a uni-lateral absorption or release of moisture by the in-s formation carrier and which result in warping of the information carrier. A comparatively small extent of j warping over a large surface area of the plate will I as a rule not exert a direct influence on the in~ormation -1 to be read, since the objective which focus~s the ¦ laser light can keep the gradually ~arying distance 1~ ~ to the optical structure within the depth of focus which j is a ~èw microns, if desired by a compensating gradual ~ displacement of the objective. In the case in which the :;J
~ carrier warps considerably over a smaller distance, ,~ ~ the objective can no longer follow-the varying position ¦ 20 Or ~the optical structure upon reading and the in~ormation carrier is no longer optically readable.
The flat, stif~ening, heat-conducting plate used ; ~ according to the invention can receive the above-mentioned forces without de~ormation o~ the plate ~5 occurring. An information disk manufactured according to the invention will not warp.
The method according to the invention produces .
_~ _ . . .
., :
.
.~ PIIN,8897 ~ ~.Z43~6 .. .
¦I good results in particular if the flat, stiffening, ¦ heat-conducting plate used is a metal plate or a glass plate in a thickness of 0.2-2 mm. Owing to -s the very good thermal conductivity and in addition the e~cellent thermal capacity~ a plate is to be z preferred which is manufactured from metal, such as nickel,steel or aluminium.
This applies in particular to an aluminium plate in a thickness of 0.3 to 1.3 mm.
In a further favourable embodiment of the method according to the invention the side of the flat plate remote from the information carrier is provided with a second transparent plastics information carrier com-prising a unilateral radiation-reflecting optical struc-- ture, the said side of the flat plate being connected throughout its surface to the radiation-reflecting op-; tical structure of the information carrier by means of an adhesive.
This results in an information disk carrying information on two sides which compri9es the double quantity of information, or~ in other words, has a double playing time. Moreover the further advantage is ob-tained that there is a fair chance that the macro-structured forces which may occur in the information carriers situated on both sides of the flat plate, com~
pensate each other at least partly. In this connection it is noted that life tests under ext:reme atmospheric `` ' P:~IN.88g7 ~L124396 circumstances have demonstra-ted that such an information s carrier remains entirely flat if herein a comparatively thin aluminium plate of 0.5 mm is used.
The adhesive used in the method according to the invention is of a conventional type, for example, a two-components adhesive. In an advantageous embodi-ment a radiation-curable lacquer is used, for example, an ultraviol0t-curable lacquer on the basis of acrylic acid. The thin liquid lacquer can easily be provided on one of the surfaces to be connected, for example by i means of a spraying process or a cen-trifuging process, `l~ that is to say, either on the informa-tion-carrying sur-face of the information carrier, or on the flat, stiffening, heat-conducting plate. A rapid curing of the ;, 15 laquer is possible by exposure via the transparent in-,~ , ~ formation carrier. It has been found that the radiation-Y~ reflecting layer which reflects in particular in the infrared region, still passes sufficient shortwave light, ~`~ for example ultraviolet light.
; ~ 20 ` If desired, the flat, stif~ening, heat-conduc-i~ ~ ting plate used may be provided with reinforcement ribs on the sids remote from the in~ormation carrier. An ; ~ information carrier and a plate may also be used which both have a central aperture so that the resulting ` ~ ~
information disk has a central aperture.
The invention will now be described in greater detail with reference to the drawing, in which: -' ' ~ , -1 1-' ' ' ' .
: . ` ` ' , . Pl-IN.8897 4~9~;
~,' 1 , '` .
Figure 1 is a cross sectional view of a plastics information carrier used in the method5 Figure 2 is a cross-sectional view of an in~or-. mation carrier obtained according to the invention, and Figure 3 is a cross-sectional view of another embodiment of an informatlon disk obtained according to the invention, Reference numeral 1 in Figure 1 denotes a trans-parent plastics information carrier comprising an op-I . tical structure 2 on one side. Information carrier 1 -`i .
~J 10 with optical structure 2 has a thickness of approximate-`. ly 1 mm and is manufactured from transparent polyvinyl chloride/acetate copolymer according to a known pressi.ng .process. The optical structure is crenellated and consists of small blocks 3 with intermediate-areas 4 the dimen-¦~ 15 sions of which lie in the order of magnitude of 1/u.
, ~ Optical structure 2 is covered with a vapour deposited ~J, radiation-reflecting aluminium làyer 5, approximately ~! 300 ~ thick 1 ~ .
~ ~ On the side o~ optical structure 2~ the informa-¦~ 20 tion carrier 1 is provided with a 0.5 mm thick aluminium .~ .plate 6 (Fig~ure 2) while using a layer of adhesive, not ~ : shown, for example, a two-components adhesive.
. <
The resulting information disk is shown in ,~ Figur.e 2. The disk is read optically and in re~lection :. .
¦~ 25 by mean: o~ laser light in the direction denoted by an ~ arrow.
.
Re~erenoe numeral 7 in Figure 3 denotes a 0.5 mm PHN.8897 ~;24396 !
thick aluminium plate provided on both sides with plastics information carriers, referenced 8 and 9, , respectively. Information carr:iers 8 and 9 correspond i to that shown in Figure 1 and are provided on one ' 5 side with an optical structure 10, 11 covered by a vapour-deposited aluminium layer, not shown. Infor-mation carriers 8, 9 are connected to plate 7 on the side o~ the optical strueture 10, 11 by means of an adhesive, not shown. The information disk shown in ~igure 3 is read bilaterally in the direction denoted by arrows.
; The thickness (appro~imately 1 rnm) of the plas-tics information earriers 1(Figures 1, 2) and 8, 9 (~i-~, gure 3) is amply suffieient to keep dust particles or seratches possibly present on the ~surface beyond the ~¦~ depth of focus of the ob~ective, not sho~, which focuses the reading beam on the optical structures 2 igures 1, 2) and 10, 11 (Figure 3~).
~ .
' .
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of manufacturing an optically read-able information disk,in which a transparent plastics information carrier comprising a radiation-reflecting optical structure on one side is provided, on the side of the optical structure, with a cover plate connected thereto by means of an adhesive, characterized in that the cover plate is a flats stiffening, heat-conducting plate manufactured from inorganic material and con-nected to the information carrier throughout its surface.
2. A method as claimed in Claim 1, characterized in that the flat plate is a metal plate or a glass plate in a thickness of 0.2 to 2 mm.
3. A method as claimed in Claim 2, characterized in that the flat plate is an aluminium plate in a thick-ness of 0.3 to 1.3 mm.
4. A method as claimed in Claim 1, 2 or 3, charac-terized in that the side of the flat plate remote from the information carrier is provided with a second trans-parent plastics information carrier comprising a uni-lateral radiation-reflecting optical structure, the said side of the flat plate being connected throughout its surface to the radiation-reflecting optical structure of the information carrier by means of an adhesive.
5. A method as claimed in Claim 1, characterized in that the adhesive used is a radiation-curable lacquer.
6. An optically readable information disk consist-ing of a transparent information carrier comprising a radiation-reflecting optical structure on one side and provided, on the side of the optical structure, with a cover plate; characterized in that the cover plate is a flat, stiffening, heat-conducting plate manufactured from inorganic material and connected to the informa-tion carrier throughout its surface by an adhesive.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7710162 | 1977-09-16 | ||
| NL7710162A NL7710162A (en) | 1977-09-16 | 1977-09-16 | METHOD FOR MANUFACTURING AN OPTICALLY READABLE INFORMATION DISK USING A FLAT, STIFFENING HEAT CONDUCTIVE PLATE OF INORGANIC MATERIAL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1124396A true CA1124396A (en) | 1982-05-25 |
Family
ID=19829188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA311,349A Expired CA1124396A (en) | 1977-09-16 | 1978-09-14 | Method of manufacturing an optically readable information disk |
Country Status (20)
| Country | Link |
|---|---|
| JP (1) | JPS5454003A (en) |
| AR (1) | AR216540A1 (en) |
| AT (1) | AT371278B (en) |
| AU (1) | AU523032B2 (en) |
| BE (1) | BE870476A (en) |
| BR (1) | BR7806005A (en) |
| CA (1) | CA1124396A (en) |
| CH (1) | CH637783A5 (en) |
| DD (1) | DD139774A5 (en) |
| DE (1) | DE2839395A1 (en) |
| DK (1) | DK403478A (en) |
| ES (1) | ES473343A1 (en) |
| FR (1) | FR2403617A1 (en) |
| GB (1) | GB2004404B (en) |
| IT (1) | IT1098622B (en) |
| MX (1) | MX148376A (en) |
| NL (1) | NL7710162A (en) |
| NZ (1) | NZ188406A (en) |
| SE (1) | SE438568B (en) |
| ZA (1) | ZA785080B (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4414650A (en) * | 1980-06-23 | 1983-11-08 | Sharp Kabushiki Kaisha | Magneto-optic memory element |
| DE3028498A1 (en) * | 1980-07-26 | 1982-03-04 | Röhm GmbH, 6100 Darmstadt | IMPROVED, OPTICALLY READED, INFORMATION STORAGE DISKS AND METHOD FOR THEIR PRODUCTION |
| JPS5766538A (en) * | 1980-10-08 | 1982-04-22 | Toshiba Corp | Information storage medium |
| JPS57186241A (en) * | 1981-05-11 | 1982-11-16 | Mitsui Toatsu Chem Inc | Optical information recording disc |
| JPS58108044A (en) * | 1981-12-22 | 1983-06-28 | Pioneer Electronic Corp | Optical disk |
| NL8301956A (en) * | 1983-06-02 | 1985-01-02 | Optical Storage Int | OPTICAL REGISTRATION ELEMENT. |
| DE3322131A1 (en) * | 1983-06-20 | 1984-12-20 | Polygram Gmbh, 2000 Hamburg | DISK-SHAPED, OPTICALLY READABLE INFORMATION CARRIER WITH PROTECTIVE EDGE |
| JPS61500574A (en) * | 1983-12-02 | 1986-03-27 | バロ−ス・コ−ポレ−ション | Cost-reduced optical disc record |
| JPS61214245A (en) * | 1985-03-20 | 1986-09-24 | Matsushita Electric Ind Co Ltd | Optical information recording medium |
| JPH061561B2 (en) * | 1985-08-21 | 1994-01-05 | 株式会社日立製作所 | Light disk |
| JPS6242347A (en) * | 1986-07-31 | 1987-02-24 | Sanyo Electric Co Ltd | Production of optical disk recorder |
| JPS63107589A (en) * | 1986-10-23 | 1988-05-12 | Nec Corp | Optical recording medium |
| LU87571A1 (en) * | 1989-08-23 | 1991-05-07 | Glaverbel | OPTICALLY READABLE INFORMATION RECORDING MEDIUM |
| EP0706179B1 (en) * | 1994-09-27 | 2002-12-11 | Matsushita Electric Industrial Co., Ltd. | Production process of optical information recording medium and production apparatus therefor |
| EP1258874B1 (en) * | 1994-09-27 | 2006-04-19 | Matsushita Electric Industrial Co., Ltd. | Production process of optical information recording medium |
| JP2742524B2 (en) * | 1994-10-03 | 1998-04-22 | 松下電器産業株式会社 | Optical information medium, optical information medium manufacturing method, and optical information medium manufacturing apparatus |
| DE69520920T2 (en) * | 1994-10-03 | 2001-09-27 | Matsushita Electric Ind Co Ltd | Optical information medium, as well as unit and method for its production |
| JPH08203126A (en) * | 1995-01-27 | 1996-08-09 | Nec Corp | Optical information recording medium, optical information reproducing method, and optical information recording, reproducing and erasing method |
| USRE39412E1 (en) | 1995-02-15 | 2006-11-28 | Matsushita Electric Industrial Co., Ltd. | Optical information medium, and method and apparatus for fabricating the same |
| US6680898B2 (en) | 2001-02-21 | 2004-01-20 | Todd J. Kuchman | Optical disc and method of protecting same |
| US6842409B2 (en) | 2001-02-21 | 2005-01-11 | Scratch-Less Disc Industries, Llc | Optical disc and method of protecting same |
| EP1637329A1 (en) | 2004-09-15 | 2006-03-22 | Domino Printing Sciences Plc | Droplet generator |
-
1977
- 1977-09-16 NL NL7710162A patent/NL7710162A/en not_active Application Discontinuation
-
1978
- 1978-09-07 ZA ZA785080A patent/ZA785080B/en unknown
- 1978-09-11 DE DE19782839395 patent/DE2839395A1/en active Pending
- 1978-09-12 AR AR273675A patent/AR216540A1/en active
- 1978-09-12 FR FR7826177A patent/FR2403617A1/en active Granted
- 1978-09-13 NZ NZ188406A patent/NZ188406A/en unknown
- 1978-09-13 GB GB7836652A patent/GB2004404B/en not_active Expired
- 1978-09-13 SE SE7809614A patent/SE438568B/en not_active IP Right Cessation
- 1978-09-13 AU AU39827/78A patent/AU523032B2/en not_active Expired
- 1978-09-13 DK DK403478A patent/DK403478A/en not_active Application Discontinuation
- 1978-09-13 CH CH956878A patent/CH637783A5/en not_active IP Right Cessation
- 1978-09-13 DD DD78207804A patent/DD139774A5/en unknown
- 1978-09-13 IT IT27635/78A patent/IT1098622B/en active
- 1978-09-14 BE BE190480A patent/BE870476A/en not_active IP Right Cessation
- 1978-09-14 CA CA311,349A patent/CA1124396A/en not_active Expired
- 1978-09-14 BR BR7806005A patent/BR7806005A/en unknown
- 1978-09-14 MX MX174881A patent/MX148376A/en unknown
- 1978-09-14 JP JP11243478A patent/JPS5454003A/en active Granted
- 1978-09-14 ES ES473343A patent/ES473343A1/en not_active Expired
- 1978-09-15 AT AT0667878A patent/AT371278B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| SE7809614L (en) | 1979-03-17 |
| ATA667878A (en) | 1982-10-15 |
| NZ188406A (en) | 1982-05-31 |
| SE438568B (en) | 1985-04-22 |
| AU523032B2 (en) | 1982-07-08 |
| GB2004404B (en) | 1982-01-20 |
| BE870476A (en) | 1979-03-14 |
| DD139774A5 (en) | 1980-01-16 |
| ZA785080B (en) | 1980-04-30 |
| AT371278B (en) | 1983-06-10 |
| NL7710162A (en) | 1979-03-20 |
| MX148376A (en) | 1983-04-13 |
| JPS574973B2 (en) | 1982-01-28 |
| BR7806005A (en) | 1979-04-24 |
| DE2839395A1 (en) | 1979-03-29 |
| ES473343A1 (en) | 1979-04-16 |
| JPS5454003A (en) | 1979-04-27 |
| AU3982778A (en) | 1980-03-20 |
| AR216540A1 (en) | 1979-12-28 |
| GB2004404A (en) | 1979-03-28 |
| CH637783A5 (en) | 1983-08-15 |
| IT1098622B (en) | 1985-09-07 |
| IT7827635A0 (en) | 1978-09-13 |
| DK403478A (en) | 1979-03-17 |
| FR2403617A1 (en) | 1979-04-13 |
| FR2403617B1 (en) | 1983-06-17 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |