Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
2002-08-20
2004-11-16
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S330000, C156S099000, C156S163000, C156S196000, C156S275700, C428S064200, C427S314000
Reexamination Certificate
active
06818386
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Present Invention
The present invention relates to a method for manufacturing a bonded optical disc that records information and comprises a plurality of disc substrates bonded together, such as a DVD.
2. Description of the Related Art
Disc-shaped recording media (optical discs) on which information is recorded and played back by irradiating the optical disc with a laser, such as compact discs (CD-ROMs), recordable compact disc (CD-Rs), digital versatile discs (DVD-ROMs), recordable DVD (DVD-Rs), and rewritable DVD (DVD-RWs), are well known. Optical discs such as DVD-ROMs, DVD-Rs, and DVD-RWs, on which information is recorded at a high density, typically comprise a plurality of disc substrates (normally two) bonded together by an adhesive or the like.
DVD-ROMs, DVD-Rs, and DVD-RWs must be manufactured with high dimensional accuracy because they have an extremely small range of dimensional error allowance with respect to radial-direction warping and circumferential-direction runout.
An example of a method for manufacturing this type of optical disc is shown in
FIG. 3A. A
coating solution comprising an organic colorant is coated onto the surface of a substrate
50
, which is formed by injection molding or the like, and dried (heated) to form a recording layer
52
. After the formation of the recording layer, a reflective layer and a protective layer or the like (not shown) are formed. Then, as shown in
FIGS. 3B and 3C
, a dummy substrate
54
is bonded to the substrate
50
.
In this method, heating the substrate
50
disposed with the recording layer
52
causes slight warping of the substrate
50
(i.e., there is a tendency for the recording layer
52
to stretch and for the substrate
50
to shrink). However, since the dummy substrate
54
is not warped because it is not heated (see FIGS.
3
A and
3
B), slight warping in a resultant optical disc
56
occurs when the dummy substrate
54
is adhered to the recording layer
54
(see FIG.
3
C).
SUMMARY OF THE INVENTION
The present invention has been developed taking the foregoing problem into consideration, and an object thereof is to provide a method for manufacturing a bonded optical disc in which warping of the optical disc is substantially eliminated.
The present invention provides a method for manufacturing a bonded optical disc comprising the steps of: coating a solution on a substrate; heating the coated substrate to thereby form a recording layer on the substrate; and adhering a dummy substrate to the recording layer, wherein the dummy substrate is also heated.
REFERENCES:
patent: 2000173946 (2000-06-01), None
Chea Thorl
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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