| Method for producing an optical information recording medium -> Monitor Keywords |
|
|
  Method for producing an optical information recording mediumUSPTO Application #: 20060048886Title: Method for producing an optical information recording medium Abstract: The invention provides a method for manufacturing an optical information recording medium having a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm, and being capable of recording and reproducing using a light with a wavelength of 450 nm or less, the method at least comprising: a metal reflective layer forming step for forming a metal reflective layer on a substrate; a recording layer forming step for forming a recording layer of an organic dye type on said metal reflective layer; and a cover layer forming step for forming a cover layer on said recording layer; in this order. (end of abstract) Agent: Sughrue Mion, PLLC - Washington, DC, US Inventors: Takeshi Kakuta, Takako Ozawa, Toshio Ishida, Akira Mizuta USPTO Applicaton #: 20060048886 - Class: 156233000 (USPTO) Related Patent Categories: Adhesive Bonding And Miscellaneous Chemical Manufacture, Methods, Surface Bonding And/or Assembly Therefor, Direct Contact Transfer Of Adhered Lamina From Carrier To Base, Metal Foil Lamina The Patent Description & Claims data below is from USPTO Patent Application 20060048886. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This is a divisional of U.S. application Ser. No. 10/318,015 filed Dec. 13, 2002. The entire disclosure of U.S. application Ser. No. 10/318,015 is considered part of the disclosure of the accompanying divisional application and is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a method for producing an optical information recording medium of capable of add-on type recording and reproduction with a laser light of a specified wavelength. [0004] 2. Description of the Related Art [0005] An optical information recording medium (optical disc) capable of information recording only once with a laser light is already known. Such an optical disc is also called an add-on CD (CD-R), and has a representative structure including, on a transparent disc-shaped substrate, a recording layer composed of by an organic dye, a light reflecting layer formed by a metal such as gold (metal reflective layer) and furthermore, a resinous cover layer (cover layer) laminated successively in this order. The recording of information on such a CD-R is executed by irradiating the CD-R with a laser light of a near infrared region (normally a laser light with a wavelength of approximately 780 nm), whereupon the irradiated part of the recording layer shows a local temperature elevation by light absorption to cause a physical or chemical change (e.g., a pit formation) thereby altering the optical characteristics of such part and thus recording the information. On the other hand, reading (reproduction) of the information is also executed by irradiating the CD-R with a laser light of the same wavelength same as that of the recording laser light, thereby detecting a difference in the reflectance between a part of the recording layer where the optical characteristics are changed (recorded part) and a part where the optical characteristics are not changed (unrecorded part). [0006] Recently the need for optical information recording media of a higher recording density has increased. In order to meet the need, an optical disc known as add-on digital versatile disc (DVD-R) has been proposed (described, for example, in "Nikkei New Media," separate edition "DVD", published 1995) . The DVD-R has a structure in which two discs are mutually adhered with recording layers positioned inside, each disc ordinarily including a recording layer containing an organic dye, a light reflecting layer (metallic reflective layer) and a protective layer, laminated in succession in this order on a transparent disc-shaped substrate bearing guide grooves (pre-grooves) for tracking an irradiating laser light, with a groove width (0.74 to 0.8 .mu.m) equal to or less than a half of the groove width in a CD-R, or a structure in which such disc is adhered with a disc-shaped protective substrate of a same shape with the recording layer positioned inside. On a DVD-R thus structured, recording and reproduction of information are executed by irradiation of a visible laser light (having a wavelength ordinarily within a range of 630 to 680 nm), and the recording can be achieved with a recording density higher than that of the CD-R. [0007] Recently, networks such as internet and high-vision television are rapidly increasing in popularity. Also the start of broadcasting of High Definition Television (HDTV) is forthcoming. Hence, there is a demand for a recording medium with a large capacity, capable of easily and inexpensively recording image information. Though the DVD-R is sufficiently serving as the large-capacity recording medium at present, the demand for a higher capacity and a higher density is ever-increasing, and the development of a recording medium capable of meeting those demands is necessary. For this reason, developments are being made for a recording medium with a larger capacity, capable of high-density recording with a light of a shorter wavelength than that of the DVD-R. [0008] For example, JP-A Nos. 4-74690, 7-304256, 7-304257, 8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207, 2000-43423, 2000-108513, 2000-113504, 2000-149320, 2000-158818 and 2000-228028 all disclose recording and reproducing methods for recording and reproducing information by irradiating an optical information recording medium, including a recording layer containing an organic dye, with a laser light of a wavelength not exceeding 530 nm in a direction from the recording layer toward a metallic reflective layer. In these methods, recording and reproduction of information are achieved by irradiating an optical disc, including a recording layer, which contains a porphiline compound, an azo dye, a metal azo dye, a quinophthalone dye, a trimethinecyanine dye, a dye of a dicyanobiphenyl skeleton, a coumarin compound, a naphthalocyanine compound or the like, with a laser light of blue color (wavelength 430 or 488 nm) or blue-green color (wavelength 515 nm). [0009] On the other hand, an optical disc of phase change type is known as a DVD, which is based on a system of employing a layer of an alley such as GeSbTe for the recording layer, instantaneously heating the recording layer with a laser light to cause a phase change from a crystalline state to an amorphous state and utilizing a change in the reflectance, caused by the phase change, for information recording and reproduction. A DVR system employing a DVD of such phase change type and executing recording and reproduction with a blue-violet laser was recently announced ("ISOM 2000", pp.210-211). This system achieves a certain result for the target toward a higher density. [0010] In an optical information recording medium to be employed in such an optical recording system utilizing a blue-violet laser and a pickup of a high numerical aperture (NA), in order to focus an objective lens of a high NA at the irradiation of the recording layer with a blue-violet laser light, it is preferred to use a thin cover layer through which the laser light enters. The cover layer is formed for example by a thin film, which is adhered to the recording layer with an adhesive material or a sticking adhesive material. A thickness of the cover layer, including an adhesive layer formed by the hardened adhesive material, is usually about 100 .mu.m, but is optimized according to the wavelength and the NA of the irradiating laser light. [0011] Such an optical disc at least includes a recording layer and a cover layer on a disc-shaped substrate, and, during manufacture, is subjected to an adhering step in which a cover sheet is adhered with an adhesive material such as a UV curable adhesive or a sticking adhesive material on a surface, bearing at least the recording layer, of the disc-shaped substrate, thereby forming a cover layer. However, such adhering step is susceptible to formation of a fault portion by causing an inclusion of dust in the adhesive layer, formed by adhering the above-mentioned surface bearing the recording layer and the above-mentioned cover sheet, thus resulting in a dropout in the optical disc, namely in a loss in the production yield. [0012] Also, JP-A No. 2000-67468 discloses a method of forming the cover layer by continuously forming a laminated film member of a configuration in which a laminate member formed by a transparent film and a sticking adhesive sheet is sandwiched on both surfaces between releasing films, then working the laminated film member into a disc shape to obtain a disc-shaped laminated film member, and adhering the laminated film member to the recording layer-bearing surface of optical disk substrate with a positional alignment, while peeling off the releasing film of a side in contact with the sticking adhesive sheet. [0013] With such a method, in case the laminated film member after the continuous formation thereof is wound in a roll, the laminated film member working into the disc shape tends to show a bending by such rolling or a curl, thereby leading to a cover layer having an unflat surface or an unevenness in the thickness. As a result, an optical information recording medium having such a cover layer is unable to achieve satisfactory recording characteristics or a satisfactory durability. [0014] Further, in the manufacturing process of the above-described optical information recording media, in the case of a DVD-R or a CD-R, there is a generally adopted procedure of forming a recording layer on a substrate and then forming a metal reflective layer thereon. Therefore, the surface of the metal reflective layer at the side of the recording layer is not exposed to the air. On the other hand, with a DVR, a procedure has been adopted of forming a metal reflective layer on a substrate and then forming a recording layer thereon, so that a surface of the metal reflective layer at the side of the recording layer is exposed to the air until the formation of the recording layer. The metal reflective layer is generally formed by sputtering a metal such as Ag or Al, and, if thus formed layer is exposed to the air, the surface thereof is oxidized by the moisture in the air or by the influence of temperature, whereby the surface roughness of the metal reflective layer is deteriorated. SUMMARY OF THE INVENTION [0015] In consideration of the foregoing, an object of the present invention is to provide a method for producing an optical information recording medium having a satisfactory jitter level, low noises and stable recording/reproducing characteristics. [0016] Another object of the present invention is to provide a method for producing an optical information recording medium capable, in an adhering step of adhering a surface bearing a recording layer and an adhering surface of a cover sheet with an adhesive material in manufacturing a high-capacity optical information recording medium, of preventing dust inclusion between the recording layer-bearing surface and the cover sheet, thereby preventing generation of a dropout. [0017] Still another object of the present invention is to provide a method for producing an optical information recording medium utilizing a method for preparing a cover layer including a step of winding such cover layer into a roll, capable of providing an optical information recording medium with excellent recording characteristics and an excellent durability. Still another object of the present invention is to provide a method for producing an optical information recording medium with an excellent productivity. [0018] The above-mentioned objects can be attained by the present invention to be explained in the following. More specifically, as a first embodiment, the invention provides a method for manufacturing an optical information recording medium having a track pitch of 200 to 400 nm and a groove depth of 20 to 150 nm, and being capable of recording and reproducing using a light with a wavelength of 450 nm or less, the method at least comprising: [0019] a metal reflective layer forming step for forming a metal reflective layer on a substrate; [0020] a recording layer forming step for forming a recording layer of an organic dye type on said metal reflective layer; and [0021] a cover layer forming step for forming a cover layer on said recording layer; in this order. [0022] As a second embodiment, the invention provides a method for manufacturing an optical information recording medium as described in the foregoing, wherein said light is a laser light having a wavelength of 450 nm or less, said cover layer has a thickness of 0.01 to 0.5 mm, and a time from immediately after a completion of said metal reflective layer forming step to a start of said cover layer forming step is 12 hours or less. [0023] As a third embodiment, the invention provides a method for producing an optical information recording medium as described in the foregoing, wherein said cover layer in said cover layer forming step is formed by an adhering step for adhering an adhering surface of a cover sheet onto said recording layer with an adhesive material, comprising the steps of adhering the adhering surface of said cover sheet to a surface bearing said recording layer, by peeling off a protective sheet, which is adhered in advance to a surface of said cover sheet opposite to the adhering surface thereof, from the surface of said cover layer. [0024] As a fourth embodiment, the invention provides a method for producing an optical information recording medium as described in the foregoing, wherein said cover layer forming step includes a step of adhering, onto said recording layer, a cover layer composed of a cover film provided with a sticking adhesive layer so that said sticking adhesive layer comes into contact with said surface, and wherein said cover layer is prepared through: [0025] a step of continuously providing a sticking adhesive layer containing a cross-linking agent on a surface of a cover film wound in a roll; [0026] a step of winding said cover film provided with said sticking adhesive layer again into a roll; [0027] a step of storage until a cross-linking reaction of said sticking adhesive layer is substantially terminated; [0028] a step of punching said cover film provided with said sticking adhesive layer into a disc shape; and [0029] a step of storing said cover film provided with said sticking adhesive layer of a disc shape in a stack in a substantially horizontal state; in succession. [0030] As a fifth embodiment, the invention provides a method for producing an optical information recording medium as described in the foregoing, wherein said cover layer forming step includes a step of adhering, onto said recording layer, a cover layer composed of a cover film provided with a sticking adhesive layer so that said sticking adhesive layer comes into contact with said surface, and wherein said cover layer is prepared through: [0031] a step of continuously providing a sticking adhesive layer containing a cross-linking agent on a surface of a cover film wound in a roll; [0032] a step of winding said cover film provided with said sticking adhesive layer again into a roll; [0033] a step of storage until a cross-linking reaction of said sticking adhesive layer is substantially terminated; [0034] a step of punching said cover film provided with said sticking adhesive layer into a disc shape; and [0035] a step of storing said cover film provided with said sticking adhesive layer of a disc shape in a substantially vertical state; in succession. Continue reading... Full patent description for Method for producing an optical information recording medium Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method for producing an optical information recording medium patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method for producing an optical information recording medium or other areas of interest. ### Previous Patent Application: Method for reproduction of a compnent with a micro-joint and component produced by said method Next Patent Application: Process and device for the manufacture of a primary unit pack of a wafer Industry Class: Adhesive bonding and miscellaneous chemical manufacture ### FreshPatents.com Support Thank you for viewing the Method for producing an optical information recording medium patent info. IP-related news and info Results in 0.40548 seconds Other interesting Feshpatents.com categories: Software: Finance , AI , Databases , Development , Document , Navigation , Error |
||
