WO2001007240A1

WO2001007240A1 - Method and apparatus for high speed production of replicas of a master pattern

Info

Publication number: WO2001007240A1
Application number: PCT/US2000/019015
Authority: WO
Inventors: Talmadge Steele
Original assignee: Thindisc Media, Inc.
Priority date: 1999-07-22
Filing date: 2000-07-11
Publication date: 2001-02-01
Also published as: AU6092000A

Abstract

Apparatus and method for forming thin-layer, optically readable replicas of information masters (39) having multiple spiral tracks of data precisely positioned about central hubs rely upon resinous material that cures in response to infrared and ultraviolet radiation. Rotatable workstations (15) form the replicas in the resinous material in contact with the surface topologies of the information masters (39) and also punch out boundary edges of central hubs in exact registration with the spiral tracks of the information masters (39). Subsequent ultraviolet curing of the resinous material to dimensionally-stable thermoset condition assures faithful reproductions of the information masters (39) in thin layers of cured resin that are coated with reflective material to form the flexible optically readable replicas. High speed production of such replicas is facilitated by forming the replicas on a continuous carrier sheet (27) that transfers through successive production stations including the rotatable workstations (15) where the replicas are simultaneously formed and initially punched to exacting dimensions using punches (17).

Description

METHOD AND APPARATUS FOR HIGH SPEED

PRODUCTION OF REPLICAS OF A MASTER PATTERN

Field Of The Invention: This invention relates to production of optical data storage media, and more particularly to apparatus and method for high speed production of such media on thin substrates formed on substantially continuous flexible web. Background Of The Invention:

Conventional techniques for forming optical data storage media such as so-called compact discs or CD ROMs commonly requires impressing or otherwise forming a replica of a master record on a carrier sheet about a central hub region. Conventional injection molding techniques produce the data track and hub alignment by mounting a nickle master within the mold cavity to receive the injection molding material in the region of the data tracks about the center hub. Such compact disc products are currently popular storage media for data, music, video programs, and the like, with concomitant requirements for precision concentric alignment of the tracks with the central hub about which the compact disc is designed to rotate. The data tracks comprise a continuing spiral of micro fine pitch and, reading equipment that is operatively interactive with the optical storage media for accessing the stored information may only be capable of tolerating misalignments of tracks relative to the rotational axis within a range of variations from concentricity not exceeding plus or minus 70 microns. High speed continuous web production of such compact discs has been severely hampered by the difficulties associated with aligning the tracks of the replica with the central hub formed in a continuous web production process. Accordingly, it would be desirable to speed up production capability using a continuously moving web, and to avoid the sources of error and delay attributable to forming and stamping operations commonly performed at different workstations. Summary Of The Invention:

In accordance with the illustrated embodiment of the present invention, multiple forming and die cutting stations are assembled about a rotatable drum with one or more information masters positioned at each station in accurate registration with hub-forming die cutting equipment at each station. In this way, both formation of tracks in a replica of an information master and accurate positioning of a central hub are accomplished at each workstation on the drum. A plurality of such workstations about the cylindrical surface of the drum thus greatly facilitates high speed production of multiple replicas per rotation of the drum, with highly accurate positioning of tracks and central hub per replica.

In another aspect of the illustrated embodiment of the present invention, a resinous material having both thermal and ultraviolet curing properties is selectively deposited on a substantially-continuous ly moving carrier web to form thin replicas of the information masters while in a partially thermally- cured viscous state, for rapid final curing thereafter in response to ultraviolet radiation. Thus, accurate reproductions of the information masters positioned at each workstation about the drum are preserved in the cured resin for subsequent processing and packaging as desired to form commercial manifestations of compact discs. Description Of The Drawings:

Figure 1A is a pictorial illustration of the forming and die cutting drum supporting multiple forming and die cutting workstations about the outer perimeter;

Figure IB is a pictorial illustration of an alternate embodiment of the forming and die cutting drum supporting multiple forming and die cutting work stations about the outer perimeter; Figure 2 A is an exploded pictorial illustration of an anvil roller and cutting die shown in operative position adjacent the drum;

Figure 2B is an exploded pictorial illustration of an alternative anvil and cutting die shown in operational position adjacent the drum; Figures 3a and b illustrate the front and end views of the cylindrical surface of the die cutting and forming drum;

Figure 4 is a pictorial illustration of a production line for forming and die cutting replicas of information masters in cured resin carried on a web;

Figure 5 A is a pictorial illustration of resin reservoir and deposition apparatus;

Figure 5B is a perspective view of resin printed in a selected pattern on a carrier web;

Figure 6 is a chart illustrating the processes of the present invention;

Figure 7 is a plan view of punched replicas relative to the carrier web; Figures 8a-d are, respectively, bottom, side, top, and front views of the lens cap;

Figures 9a, b are, respectively, top and side sectional views of the lens for forming a compact disc; and

Figure 10 is an exploded view of an assembly of replica, lens, and lens cap according to the present invention. Description Of The Invention:

Referring now to Figure 1A, there is shown a pictorial representation of a drum 9 that is mounted for rotation about its central axis 11. The drum 9 has a width dimension in the axial direction exceeding at least the width of at least one complete workstation 15, and optionally having such width dimension exceeding the widths of nested or angularly-aligned multiple adjacent workstations 15 positioned in spaced relationships about the periphery 13 of the drum 9. Each workstation 15 includes a punch disposed within the periphery 13 of the drum 9 with a cutting edge of each punch 17 protruding from the peripheral surface by about .005" to .025", depending upon thickness of web material. Each such punch 17 is retained within a blind recess in the periphery of the drum 9, for example, by a bolt 19 screwed into a mating threaded bore 21. The punch 17 includes semicircular segments that are aligned to produce only complementary, spaced partially circular slits 23 within continuous carrier sheet or web material 27, and to leave web material 25 intact within and between the punched slits, as shown in Figure 1A. Of course, other punch shapes may be used, such as square, diamond, triangle and the like, to provide accurate centering registration via the punched edges. However, the partial punching of a circular aperture (i.e., punching only complementary portions 23 of a complete circle, leaving intact web material 25 at fore and aft positions between slits 23) provides several advantages. First, web material does not have to be discarded at this workstation. Second, any distortion of a circular hole or aperture formed using a rotating punch predominately appears along an axis aligned with the vector movement of the rotating punch (i.e., near leading and trailing boundaries, viewed along the direction of rotation). Therefore, a major component of distortion or elongation of a hole punched in the manner described is minimized by retaining intact the segment 25 of web material inteφosed between complementary slits 23. The punched slits 23, however, retain highly accurate concentric alignment with the information tracks of the master record for later processing and mounting relative to the punched slits. As shown in the exploded view of a workstation in Figure 2 A, such punch 17 protrudes above the peripheral surface of the drum 9 sufficiently to completely penetrate a prepared carrier sheet or web 27, as later described herein, and is oriented and aligned with protrusions 29 of complementary shape on the anvil roller 31. The anvil roller 31 is disposed to rotate about its central axis 33 at an angular rate in ratio, say, 2: 1 to the angular rate of the drum 9 suitable for positioning one of a plurality of such surface protrusions 29 in alignment with each punch 17 as drum 9 and anvil roller 31 rotate in synchronism 20 at identical peripheral surface speeds. The drum 9 may have a diameter of the order of about 8 Vi" inches, and the anvil roller 31 may have an effective diameter including the protrusions 29 of about 4 ^lA", with the protrusions 29 extending above the surrounding surface of the anvil roller 31 by about .020". Of course, the relative orientation of a punch 17 and anvil on the rollers 9, 31 may be transposed to provide a punch on a roller 31 and a complementary anvil on the drum 9, as illustrated in Figures IB and 2B. An embossing or nip roller 35 may include a resilient rubber surface for resiliently urging a carrier sheet or web 27 with a thin layer thereon of partially-cured resin in a direction toward the surface of the drum 9 with sufficient force F to promote complete and faithful reproduction into the layer of resin on the carrier sheet or web 27 of an information master positioned about the protruding punch 17.

Specifically, in one embodiment of the invention, a thin information master 39 is positioned on the surface of a drum 9 at each workstation in the form of a disc of magnetic material such as nickel with a central aperture therethrough that is formed in exact concentric alignment with the tracks of data or other information on the information master 39 that is to be reproduced. The central aperture in each information master 39 is positioned in exact registration and with substantially the same dimension as the corresponding punch 17 about which it is positioned. In this way, the tracks of information formed on the information master 39 (in inverse or complementary surface topology relative to the desired surface topology in a replica embossed thereby) are positioned in exact concentric registration, within extremely close tolerances, about the punch 17. Each information master 39 may be held in position magnetically (or mechanically) on the periphery of the drum 9, about its associated punch 17 at each workstation 15 in slightly arcuate configuration that conforms to the peripheral surface of the drum 9. In another embodiment, multiple information masters 39 may be formed on a single master shim wrapped substantially around the periphery of the drum 9, with holes or apertures therein positioned about corresponding punches 17 forming multiple workstations 15.

Specifically, magnetic force may be established with which to hold the information master or masters 39 firmly in place on the surface of drum 9 by magnets positioned in the surface of the drum 9, for example, in a surface pattern as illustrated in Figure 3A. This figure illustrates the cylindrical peripheral surface of the drum 9 about a workstation 15. In this illustrated embodiment, longitudinal recesses or grooves 40 in the surface of drum 9 of magnetic material such as steel emanate from within the perimeter boundary of an individual information master 39 (but spaced away from the concentric information tracks), and such grooves are filled with magnetized ceramic or elastomeric material or rare-earth material 41 to produce magnetic lines of force oriented between magnetic sources 41 and adjacent surface plateaus of the surface of the steel drum between grooves, which magnetic lines of force intercept the nickel information master or masters 39 positioned on the peripheral surface of the drum 9 to provide the magnetic force sufficient to hold the individual information master (or combined information masters forming a single master shim) 39 firmly and securely on the surface of the drum 9. Of course, other arrangements of magnets and in other patterns (such as concentric rings about punches 17) may also be used to provide the requisite magnetic holding force to retain information masters (or a single master shim including multiple information masters) 39 firmly and securely on the peripheral surface of the drum 9. Ideally, the peripheral surface of the drum 9 beneath the data tracks of the information masters 39 should remain homogeneous to avoid forming into replica reproductions on carrier sheet 27 undesirable embossments of seams or separations attributable to underlying inhomogeneous surface anomalies of a magnetic hold down structure.

Referring additionally now to Figure 4, there is shown a simplified pictorial representation of a production line for forming the replicas of information masters 39 on a prepared substantially continuous carrier sheet or web 27 by the process illustrated in Figure 6. Specifically, a supply roll 43 of optically non-distorting plastic-film material such as cellulose triacetate or polycarbonate having good dimensional stability under tension and heat is disposed to unwind as a continuous web 27, about .003" to .024" thick and about 8 inches wide, through successive production stations of the production line. Wider webs 27 may be used in connection with multiple information masters spaced across the axial dimension of the roller 9. In the initial surface- conditioning station 45, at least one surface is suitably vacuumed to provide a clean working surface and is then abraded (e.g., by corona discharge on roller 44) in conventional manner to provide enhanced adhesion of the resinous material to be deposited thereon in coating station 47. The intermediate station 46 may provide decorative ink printing, or printing of registration marks, and the like, for UV curing under UV light source 48. At the coating station 47, resinous material is applied that has both infrared and ultraviolet curing characteristics or other actinic or chemical sensitivity to promote rapid fixation of replicas of the information masters 39 and to facilitate rapid processing of the replicas through the forming and stamping stations 15 on drum 9, and beyond. In one embodiment, the resinous material may be type ZTI-5622 (commercially available from Zeon Technologies, Inc., of Charlotte, N. Carolina) that is composed partly of UV activated cationically-cured resin composition and partly of free-radically cured resin composition.

In another embodiment, the resinous material is a UV curable compound comprising two separate UV curing chemistries which independently cure to produce inteφenetrating networks of UV activated, cationically cured epoxy functionality, and free-radical cured esters of acrylic acid. The cationic cure portion of the epoxy system is insensitive to the presence of oxygen and will surface cure rapidly under ambient conditions of elevated temperature. The cationic cure portion of the epoxy system also exhibits low shrinkage on cure. The free-radical cure resin portion produces a very high crosslink density to give a hard scratch resistant coating.

The free-radical cured portion of the formulation is described as multifunctional esters of acrylic and methacrylic acid [(meth)acrylates]. The (meth)acrylates can be made from aliphatic glycols, aliphatic glycol ethers, glycol esters, epoxies and urethanes. Higher functionality equates to a harder film but also higher shrinkage and distortion. Cationically cured epoxies exhibit only some of the cured film shrinkage for an UV curing compound and thus make up the largest percentage of the formulations. One benefit of the free radical portion of the formulation is to increase the overall cure speed. The heat of reaction generated by the free radical portion increases the temperature of the curing film and that heat accelerates the curing of the cationic portion of the formulation.

In addition to commercially-available ZTI-5622 resin composition, other examples of epoxy systems that are useful in the process and apparatus of the present invention are as follows:

Example 1. The cationic portion includes cycloaliphatic epoxy adduct with adipic acid, an aliphatic diepoxide of a glycol ether, and an epoxy monofunctional functional silane coupling agent. The free radically cured portion includes acrylic acid esters with functionality of 4 to 6, and methacryl monofunctional silane. The cationic curative may be triarylsulfonium hexafluorophophate, triarylsulfonium hexafluoroantimonate, or diaryliodonium hexafluorantimonate, or the like. The free radical photoinitiator is selected in conventional manner to fit the UV light source characteristics.

Example 2. The cationic epoxy portion includes bisphenol-A based epoxy resin, cycloaliphatic epoxy resin, and an epoxy monofunctional silane. The free radically cured portion can be an epoxy-acrylic acid oligomer with a minimum functionality of 2 and preferably 3, a multifunctional acrylic acid monomer with a functionality of four, and a methacryl monofunctional silane coupling agent. The same types of photoiniatators are used as in Example 1. Additionally a wetting agent/surfactant can be added to enhance film appearance to assure smoothness and lack of coating defects.

A totally cationic system may be used but would not produce inteφenetrating networks. Such totally cationic systems are bis-phenol A diepoxides and epoxy novolacs to give high refractive indices, in combination with cycloaliphatic epoxides and aliphatic mono-, di- and tri- epoxides. The epoxy and methacryl functional silanes are present to give good metallization characteristics but are optional as enhancements not critical to the formulation.

The resinous material is later curable to a permanent, cross-linked, thermoset, non-viscous state via heat and ultraviolet radiation, but is initially applied to the carrier sheet or web 27 as a viscous liquid in conventional manner at production station 47 in a thin-layer pattern resembling a doughnut, or annulus, as shown in Figure 5B. Specifically, a reservoir 28 of the viscous resin is disposed above a printing or deposition system including a conventional analox roller 26 and doctor blade 24, and intermediate transfer roller 32, and cylinder 30, as shown in Figure 5A. This facilitates liberation of air bubbles from the resin in preparation for delivery of a homogeneous resin composition to the carrier sheet 27 via the intermediate transfer rollers forming the resin distribution and printing or deposition system. The resin is deposited via the printing cylinder 32 in an annulus-shaped thin layer 34 of about one to three micron thickness at positions along the carrier sheet 27 that align substantially with the forming and punching workstations 15 on drum 9 in the next adjacent station 49 along the production line. The resin deposited in a selected pattern in this way (i.e., as an annulus 34 with a central void 53) eliminates attendant difficulties of later punching through resinous material that may adhere to the punches 17 and destroy dimensional precision of the punching operation. The resinous material thus deposited on carrier sheet 27 may be shielded 50 from extraneous sources of curing energy (e.g., UV and infrared radiation) up to close proximity with the drum 9 in. work station 49. The spot deposit of resin may then be partially cured in response to infrared radiation or heat directly supplied thereto in the production station 47. The resin may be preheated to about 130° ± 5° F. in the reservoir, and the drum 9 may also be heated and maintained at a temperature of about 121°- 175° F. Such partial curing maintains the thin layer of resinous material firmly adhered to the carrier sheet 27 at higher viscosity and with greater dimensional stability. The heating provided by roller 9 (and the associated information masters 39) achieves a partial curing of the resin while in contact with an information master 39. Pre-curing in this manner is beneficial to achieve faithful replication of the information master 39 and to speed up total curing (via ultraviolet radiation) in relation to defoliation or peeling of the replica from the information master 39, as later described herein. The anvil roller 31 as previously described may also be heated for operation at elevated temperature approximating the temperature of the drum 9 and information masters 39 to preserve dimensional accuracy of the mating punch parts, and to avoid thermal gradients on one and other sides of the carrier web 27.

At production station 49, the carrier sheet 27 thus prepared in the prior production stations 45, 47, as described above, is supplied to the workstations

15 on drum 9 with the annulus-shaped spot deposits 34 of partially-cured resinous material facing the punches 17 in substantial positional alignment of the central voids 53 with the punches 17 (of smaller diameter than the central voids 53). The drum 9 and punches 17 and anvil roller 31 may all be operated at elevated temperatures, as previously described, to promote further partial curing and dimensional rigidity of the spot deposits 34 of resinous material as such spot deposits of resinous material are cast/embossed with the surface topology of the information masters 39 beneath the nip roller 35 (after the central semicircular slits 23 are punched beneath anvil roller 31).

Immediately following the casting of the spot deposits 34 with the surface topology of the information master 39 beneath nip roller 35, the cast/embossed spot deposits 34 of resinous material are irradiated with ultraviolet (UV) energy from UV radiation sources 55 to complete the resin curing process and form a thermoset replica of the corresponding information master 39 firmly adhered to the underlying carrier sheet or web 27. The carrier sheet or web 27 may then transfer along path 27 from drum 9 after defoliating or peeling away from the information master 39 to proceed to the next production station 57, as shown in Figure 4. An alternate defoliation path 27' may retain the spot deposit of resin in contact with an information master 39 through approximately 180 ° of drum surface and an additional rip roller 43, as shown in Figures 1A, IB and 4. The carrier sheet or web 27 proceeds through the production stations 45, 47, 49, 57 at a rate of about 50 to 500 feet per minute, as desired. Following the defoliation or peeling away of the embossed replica from an information master after one (or two) rip rollers, then sources of ultraviolet light 55 are disposed close to the drum 9 on both sides of the carrier sheet or web 27 and ideally at least on the same side as the side thereof upon which the replica of the information master 39 is formed in order to expedite the UV curing of the resin forming the replica on the carrier web 27. Also, to protect the information masters 39 on drum 9 from being exposed to uncured resin during power failure or other break-down conditions, an additional UV light source 56 is disposed in the feed path toward drum 9 to be activated under such breakdown conditions for rapidly curing the resin deposits prior to contacting the information masters 39 on drum 9. To facilitate easy defoliation or peeling of the replica from the information master 39, one of several different coatings may be applied to the surface of the information master or masters 39 that promote easy release of a replica formed thereon with minimal adhesion, and to enhance surface hardness of the information master 39 for longer useful life. Specifically, in the course of preparing the information masters 39 for operation on drum 9 in the manner previously described, such masters 39 may be coated with a conformal, super- hard, low- friction coating of amoφhous diamond-like carbon (DLC) that exhibits diamond-like bonding structures when applied to the surface of the information master 39 via conventional electron-beam evaporation processes. Such DLC coating provides high abrasion resistance for improved tool wear and surface hardness (e.g. about 1000 to 3000 Vickers hardness). Additionally, information masters 39 with surface coatings of DLC exhibit low coefficient of friction (e.g. <0.1) and chemically inert properties for enhanced corrosion and wear resistance. In another embodiment, the surface of the information master or masters

39 may be coated with a thermoplastic material of the parylene group that is deposited at room temperature in a vacuum environment. Specifically, a gaseous reactive monomer, paraxylene, disperses throughout an evacuated deposition chamber containing the information master or masters 39 to be coated and condenses conformably on all exposed surfaces where it becomes polymerized as a continuous coating devoid of pin holes and generally stress- free (due to low temperature or room temperature processing) for low distortion of the information master. In still another embodiment of the present invention, a quartz-like coating of silicon dioxide may be deposited in conventional manner using plasma- enhanced chemical vapor deposition processing to form a glass-like highly flexible and abrasion-resistant coating. The surface energies of the coating are adjustable to yield wettable and non-wettable surfaces that are corrosion and wear resistant and of low coefficient of friction. These conventional coating processes are described in the literature (see, for example, U.S. Patents 5,298,587; 5,320,875; 5,433,786; 5,494,712).

At the production station 57, surface inspection is performed in a conventional manner, for example, using laser sources and detection apparatus 58 to identify defects prior to rolling up the replicas on the carrier web 27 into roll 59.

At another location, the roll 59 may be unwound and vacuumed and de-ionized and subjected to cleaning processes in conventional manner in preparation for vapor deposition of reflective material such as aluminum, such reflective material is vapor deposited in conventional manner onto the replicas of the information masters 39 that are formed in the cured thermoset, spot deposits 34 of resin on the carrier sheet 27. Such conventional vapor-deposition processing deposits approximately 600 Angstroms of aluminum onto the replica and the surface pits or other surface perturbations formed thereon by the information master 39 at the production station 49. After the reflective coating of aluminum is deposited onto the replica, a protective coating of lacquer for the metallized surface is applied and each replica is then ready for the final die cutting of the outside perimeter and the central hub aperture to liberate individual compact discs from the carrier sheet 27 that are then available for packaging and distribution in various configurations.

In accordance with one embodiment of the present invention, the plural replicas formed as thin layers of cured thermoset resin adhered to the carrier sheet 27 that forms the take up roll 59 may be handled en masse in roll 59 for transfer to a stamping or punching station which cuts the peripheral edge 51 of the replica and carrier sheet at approximately 5 inches, or less, in diameter, substantially centered about the spiral tracks of information in the surface of the replica.

More importantly, the central hub region of the replica is prepared for highly accurate concentric alignment with the tracks of recorded information by extracting the scrap web material 25 that is in position between the punched slits 23, as illustrated in Figure 1 A, IB, and by forming a keyway, or keyways, of various locking shapes, for example, as shown in figure 10, to eliminate the possibility of rotational movement of the replica relative to an underlying surface shield or lens. The final cutter die is shaped for forming the central hub as shown in Figure 7. Specifically, substantially semicircular punches at diametrically-opposite orientations are positioned to penetrate the carrier sheet 27 and remove the remaining diametric tabs 25 between the partially circular slits 23 while forming arch- like keyways 61 spanning the punched slits 23. The keyways 61 thus formed are accurately positioned ±.005" relative to each other and the crescent slits 23 are accurately positioned ±.0005" relative to the spiral information tracks in the replica. Of course, other keyway shapes such as triangular, arched, and the like, may also be formed in the hub region, as desired. In an alternative embodiment, the aperture in the hub region may be punched in a single operation between drum 9 and anvil roller 31 to form the semi-circular slits 23 and to form the arch-like keyways 61, thereby removing the scrap of carrier sheet 27 within the aperture without retaining the diametric tabs 25. However, such a punch operation may require pre-distortion of the punch 17 and anvil 29 components from the desired finished dimensions of the hub aperture in order to compensate for shrinkage of the carrier web 27 in response to relaxed tension and reduced temperature following the embossing and punching operations on drum 9, as previously described.

Each of the individual replicas cut from the carrier sheet 27 may be mounted between a surface shield, or lens, and a lens cap that forms the central hub, as shown in Figures 8a-d, 9a, b, and 10. Specifically, the lens cap 60, as shown in Figures 8a-d, includes a central race or cylindrical surface 63 that exactly conforms to the circular diameter of the punched slits 23, and includes semi-circular protrusions 65 at 180° orientations that fit within the semi-circular keyways 61 cut through the carrier sheet 27 between slits 23, as previously described. Of course, the protrusions 65 would be of shape and spacing matching keyways of other shapes punched into the central hub region, as previously described. The upper edge of the race 63 may be chamfered for easy insertion into the mating aperture in an individual replica. A wider base flange 67 below the central race 63 supports the replica thereon, and a set of 4 equally- spaced lugs or protrusions 69 surround the central aperture 71 and extend upwardly from the central race 63. A replica formed as previously described and punched out of the carrier sheet 27 thus includes a central aperture formed by the partially circular slits 23 and the semi-circular keyways 61 between slits 23 that exactly conform to the dimensions and configuration of the central race 63 and protrusions, or keys, 65 of the lens cap 60. Slight chamfers 73 at extreme outer dimensions of the protrusions 65 serve as finger grips to facilitate final handling and assembly onto the surface shield or lens 75, as shown in Figures 9a, b.

Referring now to Figure 9a, there is shown a plan view of the lens 75 which is formed as a disc of clear polycarbonate or other optically clear material such as methyl methacrylate, and the like, to a thickness of about 0.9 mm and diameter of about 120 mm. For focal lengths of the order of 1.2 mm in conventional optical readers of compact discs, the thickness of lens 75 varies inversely with the thickness of the carrier web in order to maintain good focus on the spiral tracks of recorded information formed in the replica of the information master. The central aperture includes 4 equally-spaced radial recesses or slots 77 relative to the diameter of the central aperture 79 for receiving therein the upwardly extending protrusions 69 of the lens cap 60. As shown in the sectional side view of Figure 9b, the surface recess 78 receives the central race 63 of the lens cap 60 as the lens cap 60 is assembled onto the lens 75 with the replica disposed therebetween in exact concentric registration about race 63 and in keyed orientation thereon with respect to protrusions 65. The optically-clear lens 75 thus disposed adjacent the carrier sheet 27 with the embossed surface of the replica that is metallized positioned away from the lens 75 as the assembly is clamped into this final layered configuration by the upstanding protrusions 69. In this assembly, highly accurate concentric orientation of the spiral tracks on the replica with the central aperture 71 in the lens cap is preserved by exact registration of the punched slits 23 upon the race 63 well within the operational tolerances for concentricity allowed by optical readers which thus sense the data information tracks of the replica via optical illumination and reflection through the lens 75 and carrier sheet 27.

Therefore, the high-speed method and apparatus for forming optically- readable replicas of information masters assures highly precise alignment of data tracks with central hubs well within concentricity tolerance limits for optical readers. In addition, multiple curing phases for the resinous material in which the replicas are formed greatly facilitate handling of prepared blanks through high speed punching and forming operations to greatly increase production rate of precision compact discs. Of course, the disclosed process and apparatus may also be used to produce digital video discs (DVDs) and other forms of discs having continuos grooves or other analog formats formed in the replicas of an information master for operation with optical readers.

Claims

What Is Claimed Is:

1. Apparatus for forming replicas on a carrier web of master records having surface topologies including a plurality of substantially spiral tracks of surface perturbations that are representative of recorded information, the apparatus comprising: a cylindrical member having a peripheral surface and being mounted for rotation about a central axis thereof; a plurality of work stations disposed about the peripheral surface of the cylindrical member, each work station including a punch protruding from the peripheral surface for penetrating a carrier web in a selected pattern, and including a master record having a surface topology representative of recorded information, the master record being positioned about the punch on the peripheral surface of the cylindrical member; a punch roller disposed adjacent the peripheral surface for rotation about a central axis thereof that is substantially parallel to the central rotational axis of the cylindrical member, the punch roller including at least one anvil thereon having shape corresponding to a protruding punch and disposed for cooperative engagement with a protruding punch for exerting force to penetrate a carrier sheet inteφosed therebetween in the selected pattern; a nip roller spaced from the punch roller and disposed adjacent the peripheral surface for rotation about a central axis thereof that is substantially parallel to the central rotational axis of the cylindrical member, the nip roller including a resilient surface disposed to exert force on a carrier web inteφosed between a master record and the resilient surface.

2. Apparatus according to claim 1 including a magnetic structure disposed on the peripheral surface for retaining thereon a master record of magnetic material in conformal orientation on the peripheral surface.

3. Apparatus according to claim 1 wherein the master records about each of the plurality of punches comprise portions of a single master shim disposed substantially about the peripheral surface.

4. Apparatus according to claim 1 in which the selected pattern includes spaced arcuate segments forming a partial substantially circular configuration with substantially diametrically-aligned segments devoid of punch capability to penetrate a carrier web.

5. Apparatus according to claim 4 in which the anvil carried on the punch roller protrudes toward a punch for cooperating therewith to penetrate a carrier web inteφosed between the cylindrical member and the punch roller.

6. Apparatus as in claim 5 coupled to the cylindrical member and to the punch roller for synchronizing peripheral rotations thereof to maintain recurring alignments of an anvil on the punch roller with a punch on the cylindrical member.

7. Apparatus according to claim 1 including a plurality of punches and master records thereabout on the peripheral surface of the cylindrical member, and a plurality of anvils carried on the punch roller for operative engagement with the punches on the cylindrical member.

8. Apparatus according to claim 1 including feeder apparatus disposed to supply a length of carrier web at a location inteφosed between the peripheral surface and the punch roller for penetrating the carrier web in the selected pattern.

9. Apparatus according to claim 8 in which the feeder apparatus includes a deposit station at a location along the length of carrier web preceding the punch roller for depositing on the carrier web a layer of material for forming therein a replica of the surface topology of a master record, the layer being deposited in annulus configuration excluding material in a central region of the deposit for alignment about a punch on the peripheral surface.

10. Apparatus according to claim 1 including a coating on the surface of each master record to promote defoliation of a replica from the master record.

11. Apparatus according to claim 9 for operation with said material that is responsive to ultraviolet energy to retain a replica of the surface topology of a master record formed therein, the apparatus comprising: a source of ultraviolet energy disposed adjacent the peripheral surface proximate the embossing roller for irradiating the material deposited on the carrier web following formation in the material of said replica of the surface topology of a master record.

12. Apparatus according to claim 9 for operation with said material that is responsive to thermal energy to increase viscosity in response to applied heat, the apparatus comprising: a source disposed to apply heat to the material not later than formation therein of the replica of the surface topology of a master record.

13. Apparatus according to claim 12 comprising: a heater disposed to heat the master cylinder.

14. Apparatus according to claim 12 comprising: a source disposed to supply heat to the material on the carrier web prior to formation in the material of a replica of the surface topology of the master record.

15. Apparatus according to claim 11 comprising: a coating station disposed to deposit a layer of a reflective substance on the surface of the material having formed therein a replica of the surface topology of the master record.

16. Apparatus according to claim 1 including a punch disposed to penetrate the carrier web adjacent the selected pattern to form a substantially circular aperture in the carrier web with diametrically-oriented lobes of greater dimension than the circular aperture.

17. Apparatus for supporting and positioning a carrier sheet having a plurality of substantially spiral tracks of recorded information formed thereon and including a central aperture concentric with the tracks, the apparatus comprising: a hub having a central bore therethrough and having an outer surface configured to align within a central aperture of a carrier sheet, and having substantially same dimensions as the aperture; the hub including a lower flange extending radially outwardly beyond the outer surface, and including protuberances extending above the outer surface substantially aligned with the central bore; a substantially planar lens having a central bore and including radial recesses in the central bore disposed to receive therein the protuberances of the hub for aligning the hub and lens about a central bore therethrough to position a carrier sheet between the lower flange and lens in substantially concentric alignment of the tracks with the central bore through the hub.

18. A method for forming in a layer of material on a carrier web a replica of an information master having surface topology including substantially spiral tracks representative of recorded information, the method comprising: depositing on the carrier web in a selected pattern a layer of a material having actinically-responsive viscosity; supplying actinic energy to the layer of material to increase the viscosity thereof on the carrier sheet; embossing the surface topology of the information master to form a replica thereof in the layer of material of increased viscosity, and substantially simultaneously therewith; penetrating the carrier sheet in a selected pattern near a central region of the replica formed in the layer of material; and supplying actinic energy to the layer of material having the replica formed therein to form thermoset cross-linked material for maintaining the replica of the information master.

19. The method according to claim 18 wherein: penetrating the carrier sheet in the selected pattern includes punching complementary crescents spaced by intact carrier sheet at positions corresponding substantially to uniform radial orientations about a central reference for the spiral tracks.

20. The method according to claim 18 wherein the material is actinically sensitive to heat and to ulta violet radiation; and initially supplying actinic energy includes supplying heat to the material to increase the viscosity thereof; and subsequently supplying actinic energy includes supplying ultraviolet radiation to the material following formation therein of the replica of the surface topology of the information master to form thermoset, cross-linked material to maintain the replica as formed.