Printed matter – Method
Reexamination Certificate
2000-09-25
2001-08-28
Fridie, Jr., Willmon (Department: 3722)
Printed matter
Method
C285S091000, C285S114000, C428S065200, C369S044240
Reexamination Certificate
active
06279959
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to optical discs, producing methods and production apparatuses of the optical discs, and particularly, relates to plural substrate type optical disc composed of at least two substrates joined together, wherein information tracks and a watermark can be visually observed simultaneously from a reproduction side of the optical disc.
DESCRIPTION OF THE RELATED ART
Presently, the optical disc is widely used because of its vast amount of recording capacity and convenience of handling.
In an optical disc referred to as a compact disc (CD), an information signal is recorded on only one surface (information signal recording surface) thereof and the recorded information is reproduced by irradiating a laser beam from the other surface (signal reproducing surface) side.
Recently, forgeries of optical discs have been rampant in the market. Thus, the disc sales industry is making a great effort to develop disc forgery prevention technics.
For the purpose of preventing the disc forgery and increasing an amount of recording capacity, there has been recently developed a new type optical disc referred to as a digital versatile disc (DVD, or referred to as digital video disc). However, the countermeasure employed therein is not very effective to prevent forgeries of the optical disc.
Specifically, the countermeasure thereof is as follows.
Such an optical disc has two substrates joined together with an adhesive and one of the substrates has an information recording surface on which an information signal is recorded. Upon fabrication, on the information recording surface, there is provided with a mark, a picture, letter or the like, each having a size being visually observable in the production process thereof.
When a forgery of the optical disc appears in the circulation market, it is possible to identify the forgery from the genuine one by visually inspecting from the reproduction side of the DVD, the watermark formed as a mark, a picture or a letter formed in an area of the information tracks spirally or coaxially formed.
When the watermark is visually identified, the DVD is genuine, and when not visible, such a DVD is the forgery. Thus, it is possible to prevent forgery by rejecting it from the market.
The methods for forming such a watermark are disclosed, for instance, in Japanese Patent Laid-open Publication 59-177739, Japanese Patent Laid-open Publication 2-179941, Japanese Patent Laid-open Publication 8-31020, Japanese Patent Laid-open Publication 8-55370, and Japanese Patent Laid-open Publication 9-63135.
However, in the methods of the prior arts, the watermark is directly formed on the information signal recording surface of the optical disc as uneven steps (juts and dents) of the mark, picture, letter or the like, each having a size capable of being visually observed.
Accordingly, it is easy to produce a forgery of this kind of optical disc by duplicating the information signal surface thereof precisely, resulting in a weak countermeasure against the forgery.
SUMMARY OF THE INVENTION
Accordingly, a general object of the present invention is to provide an optical disc and producing method thereof, in which the above disadvantages have been eliminated.
A specific object of the present invention is to provide an optical disc carrying a watermark having a forgery prevention effect and the producing method thereof without providing any physically uneven steps on the information disc because the watermark disappears upon producing the forgery of an optical disc.
An another and more specific object of the present invention is to provide an optical disc producing method for producing an optical disc comprising a transparent substrate having an information signal recorded surface, a reflective layer formed on the information signal recorded surface thereof, an adhesive layer formed on the reflective layer and a dummy transparent substrate on the adhesive layer stacked in this order, the method comprising the steps of: forming the reflective layer on the information signal recorded surface of the transparent substrate: coating an adhesive on the reflective layer to form the adhesive layer, wherein a curing speed of the adhesive is changeable according to a controlled amount of irradiation of electromagnetic radiation rays; disposing the dummy transparent substrate on the transparent substrate sandwiching the reflective layer and the adhesive layer; disposing a mask member over a top surface of the dummy transparent substrate, wherein the mask member has a specific masking pattern for partially shielding the electromagnetic radiation rays; and irradiating the electromagnetic radiation rays on the adhesive layer through the mask member to cause the adhesive to be cured by controlling an amount of irradiation of the electromagnetic radiation corresponding to the specific masking pattern, hereby a position of the reflective layer is microscopically and partially displaced corresponding to the specific masking pattern from an original position of the reflective layer, and thus displaced reflective layer visually exhibits a watermark having the specific masking pattern after the adhesive is cured.
Other and more specific object of the present invention is to provide an optical disc producing method for producing an optical disc comprising a transparent substrate having an information signal recorded surface, a reflective layer formed on the information signal recorded surface thereof, an adhesive layer formed on the reflective layer and a dummy transparent substrate on the adhesive layer stacked in this order, the method comprising the steps of: forming the reflective layer on the information signal recorded surface of the transparent substrate; coating an adhesive on the reflective layer to form the adhesive layer, wherein a curing speed of the adhesive is changeable according to a controlled amount of irradiation of electromagnetic radiation rays; disposing the dummy transparent substrate on the transparent substrate sandwiching the reflective layer and the adhesive layer; forming a mask pattern directly on a top surface of the dummy transparent substrate, wherein the mask pattern has a specific shape for partially shielding the electromagnetic radiation rays; and irradiating the electromagnetic radiation rays on the adhesive layer through the mask pattern formed on the dummy transparent substrate to cause the adhesive to be cured by controlling an amount of irradiation of the electromagnetic radiation rays corresponding to the specific shape, whereby a position of the reflective layer is microscopically and partially displaced corresponding to the specific shape from an original position of the reflective layer, concealing the mask pattern from the dummy transparent substrate; and thus displaced displacement of the reflective layer visually exhibits a watermark having the specific shape after the adhesive is cured.
Other and more specific object of the present invention is to provide an optical disc producing method for producing an optical disc comprising a transparent substrate having an information signal recorded surface, a reflective layer formed on the information signal recorded surface thereof, an adhesive layer formed on the reflective layer, a mask layer on the adhesive layer and a dummy transparent substrate on the mask layer stacked in this order, the method comprising the steps of: forming the reflective layer on the information signal recorded surface of the transparent substrate; coating an adhesive on the reflective surface to form the adhesive layer, wherein a curing speed of the adhesive is changeable according to a controlled amount of irradiation of electromagnetic radiation rays; disposing the dummy transparent substrate on the adhesive layer sandwiching the mask layer therebetween, wherein the mask layer has a specific pattern for partially shielding the electromagnetic radiation rays; and irradiating the electromagnetic radiation rays on the adhesive layer through the mask layer to cause the adhesive to be cured by controll
Anderson Kill & Olick P.C.
Fridie Jr. Willmon
Victor Company of Japan Ltd.
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