Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-05-28
2001-05-01
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S273700, C156S275500, C156S275700, C156S567000, C156S285000
Reexamination Certificate
active
06224702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing an optical disc, more particularly to a method of manufacturing the optical disc by bonding an upper disc plate and a lower disc plate.
2. Prior Art
Computers have made a dramatic leap forward in processing capacity and processing speed. Particularly, storage density of a storage medium has been dramatically improved. Among storage memories, a so-called storing disc, particularly an optical disc is convenient to be carried and has various uses as a storage memory.
An optical disc is generally structured by a discoid substrate made of a synthetic resin such as polycarbonate. Signal pits as information signals are generally recorded in the disc substrate, and a reflecting film such as aluminum, nickel, etc. are formed on signal pits. A protecting resin layer, such as UV curing resin (a so-called UV resin) is formed on the reflecting film so as to protect the signal pits.
The thickness of the disc substrate is generally 0.6 mm in view of storage of signals, manufacturing limitation and strength of the disc substrate. Accordingly, if two pieces of disc substrates each having 0.6 mm in thickness are bonded by an adhesive, the thickness becomes 1.2 mm that is a standard of a compact disc.
Meanwhile, the inventors of the present invention developed a system (U.S. Pat. No. 5,779,855) which comprises a series of processes including an adhesive spreading step and an adhesive curing step in a method of manufacturing an optical disc.
In the system, there are employed processes for bonding two disc substrates, then irradiating the adhesive with UV to cure the adhesive in a state where they are pressed by UV transmittance plates from the upper and lower sides thereof.
In the system, two disc substrates are irradiated with UV and an adhesive is cured while the substrates are moved by a belt conveyer in a curing unit in a state where they are placed on a base table.
After the two disc substrates are passed away from the curing unit, the UV transmittance plates are taken out and bypassed from a main stream of process, then the two disc substrates are delivered to a bonding unit by another belt conveyer.
The base table from which the UV transmittance plates are taken out are fed to the bonding unit by a belt conveyer and two new disc substrates are placed on the base table.
The UV transmittance plates which were taken out from the base table and bypassed from the mainstream are placed on the two new disc substrates. The two new disc substrates are fed to the curing unit, and these operations are repeated.
According to the system set forth above, two disc substrates are placed on the base table and moved by the belt conveyer so that the two disc substrates become unstable in motion.
Particularly, since the two disc substrates are irradiated with UV while they are moved in the curing unit by the belt conveyer in a state where they are placed on the base table, the irradiation time becomes long and the two disc substrates are susceptible to heating by a light source incorporated into the curing unit. Further, since the UV transmittance plates in addition to the base table are moved by the belt conveyer, the conveying or delivering part occupies a large space in the system which is inefficient in view of consumption of energy.
SUMMARY OF THE INVENTION
The present invention solved the problems of the prior art method of manufacturing an optical disc.
That is, it is an object of the present invention to provide a method of manufacturing an optical disc capable of speeding up the curing of an adhesive and of reducing an area or space occupied by a curing unit in the optical disc manufacturing apparatus as much as possible.
It is another object of the present invention to provide a method of manufacturing an optical disc which is not susceptible to heat from a curing unit or a UV irradiation unit while an adhesive is cured.
To solve the above problems, the inventors of the present invention endeavored themselves to study these problems of the prior art method and have found out that if a turntable is used instead of a belt conveyer, it can solve the problems of curing speed and the space problem of a curing unit as set forth above. Further, the inventors also have found out that a UV light source can be separated from the disc substrate by use of a turntable.
That is, it is a first aspect of the invention to provide a method of manufacturing an optical disc comprising a step of supplying lower and upper discs, a step of spreading an adhesive between the lower and upper discs, and a step of irradiating the adhesive spread between the lower and upper discs with UV, wherein the irradiation step is performed on a turntable.
In the method in the first aspect of the invention, the irradiation step is performed by a UV irradiation unit having a light source provided away from the turntable.
It is a second aspect of the invention to provide a method of manufacturing an optical disc comprising a step of supplying lower and upper discs, a step of spreading an adhesive between the lower and upper discs, a step of placing bonded lower and upper discs on a UV transmittance table, said UV transmittance table being disposed so as to cover a through hole of a turntable, a step of placing the bonded lower and upper discs on a UV transmittance plate, a step of irradiating the bonded lower and upper discs with UV from the lower side of the UV transmittance table and from the upper side of the UV transmittance plate at the same time so as to cure the adhesive to form an optical disc, a step of taking up the optical disc from the UV transmittance plate, and a step of taking out the bonded lower and upper discs from the UV transmittance plate.
The method according to the second aspect of the invention further includes a step of inspecting the tilting of the optical disc.
In the method according to the second aspect of the invention, the taking out step is performed on the same turntable.
In the method according to the second aspect of the invention, the irradiation step is performed by a UV irradiation unit having a light source provided away from the turntable.
In the method according to the second aspect of the invention, the irradiation step is performed in a manner that a gas generated when the adhesive is cured is sucked by a hood surrounding the bonded upper and lower discs.
In the method according to the second aspect of the invention, the UV transmittance plate is placed on the turntable.
In the method according to the second aspect of the invention, the continuous steps from the disc placing step on the UV transmittance table to the optical disc taking out step include a step of centering the UV transmittance table, UV transmittance plate and bonded disc substrates by a boss which is inserted into the UV transmittance plate and the central holes of the bonded disc substrates, thereby expanding inner surfaces of the holes outward.
The method according to the second aspect of the invention further comprises a boss provided on the UV transmittance table for centering the UV transmittance table, UV transmittance plate and bonded disc substrates.
In the method according to the second aspect of the invention, the UV transmittance plate is quartz glass.
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patent: 4877475 (1989-10-01), Uchida et al.
patent: 4990208 (1991-02-01), Kano
patent: 4995799 (1991-02-01), Hayashi et al.
patent: 5197060 (1993-03-01), Yatake
patent: 5364256 (1994-11-01), Lipscomb et al.
patent: 5597519 (1997-01-01), Martin et al.
patent: 5681634 (1997-10-01), Miyamoto et al.
patent: 5716761 (1998-02-01), Iida et al.
patent: 5779855 (1998-07-01), Amo et al.
patent: 5785793 (1998-07-01), Arai et al.
patent: 5888433 (1999-03-01), Amo
patent: 6108933 (2000-08-01), Vromans et al.
Amo Mikuni
Kitano Ryoko
Ball Michael W.
Flynn ,Thiel, Boutell & Tanis, P.C.
Kitano Engineering Co., Ltd.
Tolin Michael A.
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