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US 5,273,598 AGranted
Optical disc manufacturing method
AssigneeHitachi Maxell, Ltd.
InventorsToshio Higasihara, Ken Yoshizawa, Masahiro Suzuki, Akira Gotoh, Yoshitane Tsuburaya
Life of this patent
Estimating the term…
Abstract
An optical recording disc which includes a pair of recording disc substrates opposed to each other with a space there between with a hub situated at the central portion of the disc substrates so that there is formed the closed space between the disc substrates, thereby providing a dual sided recordable optical recording disc. The hub may be formed by a pair of hub halves. There is disposed an annular inner spacer and annular outer space around the hub so as to separate the pair of recording disc substrates.
Claims16
A process of making an optical disc comprising the steps of:
- arranging a first hub half having a center hole at the center of a first disc substrate,
- arranging a second hub half having a center hole at the center of a second disc substrate,
- forming a first layer having at least tracking information on said first disc substrate by using a center portion of said first hub half as a reference point arranging a spindle projected from a surface of a stamper,
- forming a second layer having at least tracking information on said second disc substrate by using a center portion of said second hub half as a reference point arranging a spindle projected from a surface of a stamper,
- forming a first recording layer and a second recording layer respectively on each of said first and second layers having tracking information thereon,
- positioning said first and second disc substrates by using said center holes of said first and second hub halves making said first disc substrate face said second disc substrate so that said first recording layer faces said second recording layer, and
- constructing said first substrate with said first hub half and said second substrate with said second hub half as one body.
4 more elements
A process of making an optical disc comprising the steps of:
- producing a first optical disc including a first transparent substrate having a first rotation central hole defined at the center of said first transparent substrate, a first hub half having a central hole with a rotation center and a first projected portion joined to a first inner surface of said first transparent substrate with a first cylindrical portion of said first hub half projecting through said first rotation central hole juxtapositioned to a second surface of said first transparent substrate circumscribing said first rotation central hole, said rotation center of said first hub half central hole accurately coinciding with said first rotation central hole of said first transparent substrate,
- producing a second optical disc including a second transparent substrate having a second rotation central hole defined at the center of said second transparent substrate, a second hub half having a central hole with a rotation center and a second projected portion joined to a first inner surface of said second transparent substrate with a second cylindrical portion of said second hub half projecting through said second rotation central hole juxtapositioned to a second surface of said second transparent substrate circumscribing said second rotation central hole, said rotation center of said second hub half central hole accurately coinciding with said second rotation central hole of said second transparent substrate,
- providing at least one recording layer for recording tracking signals on at least one surface of said first transparent substrate and said second transparent substrate,
- arranging said first optical disc with respect to said second optical disc such that a central axis of tracking coincides with a central axis of said first rotation central hole of said first hub half of said first substrate and a central axis of said second rotation central hole of said second hub half of said second substrate,
- bonding an outer surface of said projected portion of said first hub half of said first optical disc and an outer surface of said projected portion of said second hub half of said second optical disc,
- engaging a ring like inner spacer having an inner cylindrical surface with outer peripheral sides of said first projected portion of said first hub half and said second projected portion of said second hub half, and bonding said inner cylindrical surface of said ring like inner spacer to said projected portions of said first hub half and said second hub half, and
- bonding a first end surface of said inner spacer of said surface of said first transparent substrate and a second end surface of said inner spacer to said surface of said second transparent substrate.
4 more elements
A method of producing an optical recording disc comprising the steps of:
- providing a stamper having at least prepits and/or pregrooves formed on a surface thereof including a positioning pin projected from a center of said surface, an axial center of said pin coinciding with a tracking center and a rotation center of said optical disc,
- coating an ultraviolet-hardenable resin layer on said surface of said stamper over said prepits and/or pregrooves,
- providing a transparent disc substrate having a surface with a through hole formed at a center thereof,
- providing a hub comprising a central hole and a cylindrical portion, said hub having a flange portion as an outer extension of said cylindrical portion, said central hole being arranged at a center of said cylindrical portion,
- inserting said hub into said through hole of said disc substrate such that said flange portion and an outer rim surface of said cylindrical portion of said hub bonds said hub to said disc substrate,
- positioning said disc substrate over the resin layer coated surface of said stamper by inserting said positioning pin of said stamper into said central hole of said hub,
- uniformly radiating said transparent disc substrate with ultraviolet radiation while said disc substrate is positioned on said surface of said stamper thereby hardening said resin,
- exfoliating said hub and said transparent disc substrate from said stamper whereby said hardened resin layer separates from said stamper with said disc substrate, said hardened resin layer comprising a surface of pregrooves and/or prepits, and
- forming a recording layer on said surface of said hardened resin layer over said pregrooved and/or prepitted surface.
6 more elements
Dependencies are inferred from the claim text.