News Column

Researchers Submit Patent Application, "Optical Recording Medium Substrate, Optical Recording Medium, and Method of Manufacturing Optical Recording...

June 5, 2014



Researchers Submit Patent Application, "Optical Recording Medium Substrate, Optical Recording Medium, and Method of Manufacturing Optical Recording Medium Substrate", for Approval

By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Nakayama, Hiroshi (Miyagi, JP); Takemoto, Hiroyuki (Miyagi, JP); Kikuchi, Minoru (Miyagi, JP); Matsuura, Minoru (Miyagi, JP), filed on November 8, 2013, was made available online on May 22, 2014.

The patent's assignee is Sony Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "The present disclosure relates to an optical recording medium substrate that reduces warpage, an optical recording medium using the optical recording medium substrate, and a method of manufacturing the optical recording medium substrate.

"An optical recording medium is very excellent as a medium for supplying software (including music, videos, etc.), and has become widespread in a comprehensive range of fields due to the convenience of handling, the ease of mass production, the reduction of manufacturing cost, etc. In addition, improvement in high density of an optical recording medium is in progress, and a Blu-ray disc (registered trademark) or the like implementing a significantly high capacity compared to, for example, a compact disc (CD) and a digital versatile disc (DVD) of the related art, has become widespread.

"When these optical recording media are warped, it is difficult to exhibit good reproduction characteristics. This is because aberration occurs in a light spot.

"In Japanese Unexamined Patent Application Publication No. 2009-271970, technology for laminating an optical transmission layer (transparent cover layer) formed by an active energy line curable resin having predetermined characteristics in order to suppress the warpage of an optical recording medium (particularly, a Blu-ray disc) has been disclosed."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Incidentally, when the optical recording medium of the related art does not have sufficient rigidity and, for example, is stored for a long period of time in a horizontal state in which both ends of the optical recording medium between which the center is interposed are inserted into holding grooves of a storage cartridge, there is a possibility of warpage occurring and it is difficult to exhibit good reproduction characteristics. In storage in a high-temperature environment, this may be remarkably shown. This is one factor shortening a life of the optical recording medium. If the warpage of the optical recording medium stored in such a horizontal state can be reduced, this will greatly contribute to long-term storage of the optical recording medium.

"It is desirable to provide a long-life optical recording medium substrate which reduces warpage and has good reproduction characteristics even when an optical recording medium is stored for a long period of time in a normal- or high-temperature environment in a horizontal state, and an optical recording medium using the same.

"According to an embodiment of the present disclosure, there is provided an optical recording medium substrate including a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 2520 C. is in a range from 1.1930 g/cm.sup.3 to 1.2000 g/cm.sup.3.

"According to another embodiment of the present disclosure, there is provided an optical recording medium including an optical recording medium substrate which is a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25.degree. C. is in a range from 1.1930 g/cm.sup.3 to 1.2000 g/cm.sup.3.

"Further, according to still another embodiment of the present disclosure, there is provided a method of manufacturing an optical recording medium substrate, including filling and injection-molding a polycarbonate in which an average molecular weight is in a range from 15000 to 16000 in a mold, and performing cooling in the mold for 6 seconds or more.

"Thereby, high rigidity of the optical recording medium is secured. According to one or more embodiments of the present disclosure, even when an optical recording medium is stored for a long period of time, warpage due to its own weight can be suppressed and music, videos, etc. recorded on the optical recording medium can be reproduced in a good state.

"In addition, even when the optical recording medium is stored in a high-temperature environment, it is possible to suppress warpage due to its own weight and similarly obtain good reproduction characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is an explanatory diagram of a layer structure of an optical recording medium of an embodiment;

"FIG. 2 is a diagram illustrating a method of measuring a density of an optical recording medium substrate;

"FIG. 3 is a diagram illustrating a change in a shape when the optical recording medium is held in a horizontal state;

"FIG. 4 is a diagram illustrating a measurement result of warpage of the optical recording medium when stored in the horizontal state;

"FIG. 5 is a diagram illustrating a relationship between a density and warpage of the optical recording medium substrate; and

"FIG. 6 is a diagram illustrating a relationship between a cooling time in injection molding of the optical recording medium substrate and a density."

For additional information on this patent application, see: Nakayama, Hiroshi; Takemoto, Hiroyuki; Kikuchi, Minoru; Matsuura, Minoru. Optical Recording Medium Substrate, Optical Recording Medium, and Method of Manufacturing Optical Recording Medium Substrate. Filed November 8, 2013 and posted May 22, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2864&p=58&f=G&l=50&d=PG01&S1=20140515.PD.&OS=PD/20140515&RS=PD/20140515

Keywords for this news article include: Sony Corporation.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Politics & Government Week


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters