Apparatus and process for producing optical recording medium

Details Apparatus and process for producing optical recording medium Apparatus and process for producing optical recording medium

1999-06-24

2001-08-28

Vargot, Mathieu D. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Optical article shaping or treating

Light polarizing article or holographic article

C264S002500, C264S106000, C264S001360, C264S102000, C425S126100, C425S174400, C425S810000

Reexamination Certificate

active

06280661

ABSTRACT:

TECHNICAL FIELD
The present invention relates to an art suitable for production of an optical recording medium having convex-concave patterns formed in the surface thereof. More particularly, the present invention is intended to provide a production apparatus that enables reduction in the number of steps of a process for producing an optical recording medium by making use of a method known as 2P (photo polymerization) method.
BACKGROUND ART
Hitherto, 2P method has been known as a typical process for producing optical recording media, i.e., optical disks. The 2P method has the steps of preparing a flat plate such as of glass (referred to as a “flat substrate”, hereinafter), filling the gap between the flat substrate and a stamper with a photo-curable resin that can be cured by energy of light rays such as ultraviolet rays, and irradiating the resin with ultraviolet rays thereby curing the resin.
An example of such a 2P method is disclosed in Japanese Unexamined Patent Application Publication No. 53-86756. The art disclosed in this patent publication uses a mold which is formed from nickel by electroforming (the term “mold” is used to mean a member equivalent to a stamper, throughout the specification). A pattern is transferred from this mold to a flat substrate made of polymethylmethacrylate, polycarbonate or the like, by means of a resin curable by ultraviolet rays.
In the meantime, Japanese Unexamined Patent Application Publication No. 5-62254 discloses a method which uses a mold made of silicon. In this method, a pattern composed of convexities and concavities is formed in a silicon wafer mold by etching, and this pattern is transferred to a flat substrate by means of a resin curable with ultraviolet rays.
It has been a common practice that, in carrying out these known methods, different steps of each method such as bonding of the ultraviolet-rays-curable resin and the substrate, expose, and separation are performed at different places.
Execution of different steps at different places require transportation of the substrate and the mold which consumed time to impair the efficiency of production. Unfortunately, however, the above-mentioned two patent publications fail to disclose any practical form of production apparatus which would enable efficient production.
Two types of approaches are conceivable towards a through process for producing optical disks by using 2P method: one is to produce the disks by moving the mold, while the other is to keep the mold stationed during the production of the disks. Considering that the mold is a precisely-finished part to require a considerable time for transportation, it is considered to be a better policy that the production apparatus is designed to keep the mold stationary.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide a compact apparatus for producing an optical recording medium, in which a mold is kept fixed so as to eliminate the necessity for any mold transporting mechanism, thus saving the time that has hitherto been required for transporting the mold.
It is a second object of the present invention to provide a compact production apparatus for producing an optical recording medium, in which a substrate on which curable resin has been applied is transported to the position of a mold which is fixed, thus saving the time that has hitherto been required for transporting the mold.
It is a third object of the present invention to provide an apparatus for efficiently producing an optical recording medium, wherein a mold is kept fixed so as to reduce the number of process steps through elimination of steps for clamping and unclamping the mold that have hitherto been necessary.
It is a fourth object of the present invention to provide a compact apparatus for producing an optical recording medium, in which a curing mechanism is transported to the position of a mold that is fixed, thus eliminating the necessity for any mechanism for transporting the mold and saving the time that has hitherto been required for transporting the mold.
It is a fifth object of the present invention to provide a compact apparatus for producing an optical medium, in which a substrate is separated from a mold while the mold is kept fixed, thus eliminating the necessity for any mechanism for transporting the mold and saving the time that has hitherto been required for transporting the mold.
To achieve the first object, there is provided an apparatus for producing an optical recording medium by curing a curable resin between a substrate and a mold, comprising: a mold fixing mechanism for fixing the mold; a transporting mechanism for transporting the substrate to which the curable resin has been applied to a position where the mold is fixed, and placing the substrate on the mold such that the surface of the substrate to which the curable resin has been applied faces the mold; a resin curing mechanism for curing the curable resin which has been sandwiched between the mold and the substrate by the action of the transporting mechanism; and a separating mechanism for separating the resin that has been cured by the resin curing mechanism, together with the substrate, from the mold.
According to this invention, since the mold is fixed and kept stationary, the time which otherwise would be required can be eliminated.
The mold may be made of a metal or other material such as silicon or quartz. The curable resin may be a photo-curable resin or a thermosetting resin. The resin curing mechanism may be of the type that has a function to irradiate the curable resin with light rays or a function for applying heat to the curable resin.
In order to achieve the second object, the apparatus may further comprise a resin applying mechanism for applying the curable resin to the surface of the substrate.
In order to achieve the fifth object, the resin applying mechanism applies the curable resin so as to leave part of the surface of the substrate without being coated with the curable resin.
The presence of a region devoid of the curable resin permits easy separation of the substrate after the adhesion of the cured resin thereto.
To achieve the third object, the mold fixing mechanism may further include: a hermetic vessel having an opening adapted to be covered and hermetically closed by the transporting mechanism and having a bottom adapted for carrying the mold; and a vacuum pump for evacuating the interior of the hermetic vessel.
In accordance with this arrangement, the hermetic vessel is hermetically closed by the transporting mechanism, and air is sucked from the closed hermetic vessel, thereby preventing inclusion of voids in the curable resin. The pressure inside the vessel is then recovered. The vacuum pump is connected to the hermetic vessel through a fixed pipe, whereby the pressure reduction is quickly performed.
In order to achieve the fourth object, a photo-curable resin may be used as the curable resin. In such a case, the resin curing mechanism includes an illuminating device for irradiating the photo-curable resin to cure the photo-curable resin, and an illumination shifting mechanism for shifting the illuminating device to a position near the mold.
This arrangement permits the mold to be kept stationary, since the curing mechanism is brought to the position where the mold is disposed.
In order to achieve the fifth object, the mold has an outside dimension equal to or smaller than that of the substrate, and the separating mechanism includes a gripper that grips part of the substrate so as to separate the cured resin together with the substrate from the mold.
With this arrangement, the cured resin can easily be separated from the mold together with the substrate, because the substrate can be gripped at a portion thereof.
In order to achieve the first object, the present invention also provides a method for producing an optical recording medium by curing a curable resin between a substrate and a mold, comprising the a resin applying step in which the curable resin is applied to a surface of the substrate; a transporting step for

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