Stock material or miscellaneous articles – Circular sheet or circular blank – Recording medium or carrier
Reexamination Certificate
2001-04-27
2004-11-02
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Circular sheet or circular blank
Recording medium or carrier
C428S064100, C428S064400, C428S064700, C430S270100, C430S271100, C430S286100, C369S288000
Reexamination Certificate
active
06811851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the technical field of plastic molding, particularly to a technique for forming a ridge of a resin in a desired form on a polycarbonate substrate.
2. Description of the Related Art
Hereinafter, a conventional technique for forming a ridgy resin film will be described taking an optical recording medium for example.
Reference numeral
110
in
FIG. 9
denotes an optical recording medium. The optical recording medium
110
includes a disk-shape substrate
111
made of a transparent resin. A circular hole
113
is provided at the center of the substrate
111
.
A recording layer (a reflection film) composed of a metal thin film (a reflection film) and a protective layer for protecting the recording layer are formed on the surface of the substrate
111
.
On the back surface of the substrate
111
, a resin film
120
constituted of a ridge is formed around the hole
113
. The ridgy resin film
120
takes on, as a whole, a ring form, and its center coincides with those of the hole
113
and the substrate
111
.
The ridgy resin film
120
and the substrate
111
are formed by injection molding in which a resin is injected into a cavity of a metal mold and then molded. That is, the ridgy resin film
120
and the substrate
111
are molded into a unitary body.
The above-mentioned recording layer is laid outside the ridge of the optical recording medium
110
, and the area extending outwardly of the ridge is defined as an information recording area
118
. In the information recording area
118
, information can be recorded by forming pits or grooves in other than the area where the ridgy resin film
120
has been formed.
A reader which reads out information from the optical recording medium
110
is equipped with a laser beam irradiator, and the optical recording medium
110
is placed on a tray with its ridgy resin film
120
facing downward and inserted into the device such that the recording medium goes above the laser beam irradiator.
With the optical recording medium in this position, the ridgy resin film
120
-provided side of the optical recording medium
110
is irradiated with a laser beam. The irradiated laser beam is reflected by the metal thin film and detected to read information recorded thereon.
Since the optical recording medium
110
is placed in such a manner, the ridgy resin film
120
prevents the information recording area
118
from being brought into contact with the tray and consequently being scratched. Moreover, since the surface of the optical recording medium
110
is not brought into tight contact with the tray, ejection of the optical recording medium
110
becomes easier.
However, such a metal mold as is employed in the injection molding described above is expensive, leading to an increase in the production cost of the substrate
111
.
Further, forming ridgy resin films in various forms requires the use of metal molds corresponding to their respective shapes.
For forming the ridgy resin film without using a metal mold, there may be proposed a method including applying a resin liquid containing a photoreactive resin onto the surface of the substrate and curing the resin liquid through the irradiation of ultraviolet rays.
However, according to this method, if the viscosity of the resin liquid is high, the resulting ridgy resin film will be wide. Particularly, in the case where the resin liquid is applied in the form of a ring, as described above, since the starting position of resin supply and its end position overlap and the resin liquid is supplied there excessively, the resulting film will be wide only at the point of overlap.
On the other hand, if the viscosity of the resin liquid is low, the resin liquid cannot rise from the surface of the substrate and therefore the surface of the resulting ridgy resin film will be lowered.
In any case, in the technique of applying the resin liquid, it is difficult to form a ridgy resin film which rises for a sufficient height and has an even width.
SUMMARY OF THE INVENTION
The present invention was made to solve the above-described problems faced in the prior art. An object of the present invention is to provide a process for forming a ridgy resin film uniform in width without using a mold, particularly a ring-shape ridgy resin film which is uniform in width.
For solving the above-mentioned problems, the present invention is a process for forming a ridgy resin film, comprising the steps of: forming a first concave and a second concave on a surface of a plate substrate to make an area between the first and second concaves as a resin film formation area; supplying a resin liquid containing a photopolymerizable resin onto a surface of the resin film formation area to form a resin liquid layer consisting the resin liquid; and curing the resin liquid layer to form a ridgy resin film.
The present invention is the process for forming a ridgy resin film, wherein the resin liquid layer is cured by irradiation with ultraviolet rays.
The present invention is the process for forming a ridgy resin film, wherein during the step of forming the first concave and the second concave, a boundary between the resin film formation area and the first concave and that between the resin film formation area and the second concave are raised to form ridges, and the ridgy resin film is formed between the ridges.
The present invention is the process for forming a ridgy resin film, wherein the first and second concaves are formed by scraping the surface of the substrate by pressing an excavator against the surface of the substrate.
The present invention is the process for forming a ridgy resin film, the first and second concaves are formed by irradiating the surface of the substrate with a laser beam.
The present invention is the process for forming a ridgy resin film, wherein the first and second concaves are formed in concentric relation.
The present invention is the process for forming a ridgy resin film, wherein the viscosity of the resin liquid at 25° C. is not lower than 10 mPa·s nor higher than 1,000 mPa·s.
The present invention is the process for forming a ridgy resin film, wherein the viscosity of the resin liquid at 25° C. exceeds 100 mPa·s.
The present invention is the process for forming a ridgy resin film, wherein the glass transition temperature of the resin forming the ridgy resin film is not lower than 60° C. and below 100° C.
The present invention is the process for forming a ridgy resin film, wherein the height from the surface of the resin film formation area to the surface of the ridgy resin film is 3 &mgr;m or higher.
The present invention is a process for producing a recording medium molded in the form of a disk and having a recording layer and a resin layer provided on the recording layer, the process comprising the steps of; forming ring-shaped first and second concaves on a surface of the resin layer with the center of the recording medium as the centers to form an area between the first and second concaves as a resin film formation area; supplying a resin liquid containing a photopolymerizable resin onto the resin film formation; and curing the resin liquid layer to give a ridgy resin film.
The present invention is an optical recording medium molded in the form of a disk and having a recording layer and a resin layer provided on the recording layer, wherein ring-shaped first and second concaves with the center of said recording medium as the centers, a resin film formation area between said first and second concaves, and a ridgy resin film formed in said resin film formation area are formed on a surface of said resin layer, and said ridgy resin film is raised above a surface of said resin layer.
The present invention is the recording medium, wherein the resin layer is made of a polycarbonate resin.
Since the present invention has the structure as described above and the first and second concaves formed on the surface of the substrate are spaced a given distance apart from each other, a ridgy resin film having a predetermined width can be
Konishi Misao
Tanaka Mieko
Yanagida Satoshi
Ferguson L.
Kelly Cynthia H.
Oliff & Berridg,e PLC
Sony Chemicals Corp.
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