Stock material or miscellaneous articles – Circular sheet or circular blank
Reexamination Certificate
1999-03-19
2001-12-11
Evans, Elizabeth (Department: 1774)
Stock material or miscellaneous articles
Circular sheet or circular blank
C428S064400, C428S064800, C428S913000, C430S270110
Reexamination Certificate
active
06329035
ABSTRACT:
BACKGROUND
1. Field
The present invention relates to an optical data storage medium capable of reversibly displaying information and a process of recording information for displaying on the medium.
2. Discussion of the Background
The importance of electronic data storage media in computer equipment for storing, recording and rewriting data has been increasing, in the office, home and in other environments. Such electronic data storage media include, for example, magnetic tapes; floppy disks; magneto-optic disks; compact-discs digital-audio (CD-DAs), compact disc-read-only-memory (CD-ROM), CD-Recordable (CD-Rs), CD-Rewritable (CD-RWs) and other compact disc (CD) media; digital video disc-read-only-memory (DVD-ROMs), digital video disc-recordable (DVD-Rs), digital video disc-random access memory (DVD-RAMs) and other DVD media; IC memory cards; optical cards; transportable hard discs and various other media. In addition, the types and volume of data stored in individual media have increased with increasing storage capacities. The demand has increased for optical data storage media in which data is stored and read by means of lasers.
Descriptions and volume names for the data stored in electronic data storage media are recorded as user readable indexes for the data. For such index recording, conventionally, an index label in the form of a sticker is applied onto a disc cartridge. For example, Japanese Laid-Open Patent Application (referred to as JPA, hereinafter) No. 9-282836 proposes a process of rewriting and displaying information as indexes for the stored data by using a liquid crystal/polymer composite film as an index label. In compact discs, however, the CD itself is separately used without a cartridge; if such a liquid crystal/polymer composite film is provided on the surface of the disc, the rotation of the disc is adversely affected and data might not, be reliably read or written by a laser light.
CD-ROMs, on which data have already been recorded in a production process, are used as read-only optical data storage media. In the case of CD-ROMs, indexes or various design patterns indicating the contents of stored data are printed on their protective layers with an ultraviolet-curing ink or an oil-based ink. Such indexes or design patterns are generally printed by screen printing, offset printing or other printing techniques, which are suitable for rapidly and efficiently printing the same pattern in a so-called mass printing process.
Write-once-read-many optical data storage media, such as CD-Rs, on which data can be recorded by a laser only once and the recorded data can be reproduced with a CD player, have been developed, and users have stored their own data for personal use, such as music and computer data, on CD-Rs. The CD-Rs generally have no description or only have some common characters or design patterns on their surfaces printed with an ultraviolet-curing ink or an oil-based ink. For adding description for such data for personal use, there have been proposed a process of writing the description as an index or other design patterns on a protective layer of the medium with an oil-based felt-tipped pen, for example, a process of applying a thin label onto the medium for writing the description thereupon, a process of providing an ink-accepting layer on the surface of a medium and recording the description by an ink-jet recording method (JPA-5-238005) and a process of providing a dye-accepting layer on the surface of a medium and recording the description by a sublimation thermal transfer recording process (JPA-8-48080). Each of the above processes may be carried out before or after optically recording personal data on an optical data storage medium.
Recently, optical data storage media in which stored data can be rewritten by a laser, such as CD-RWs, have been developed and come into use. When indexes or design patterns are recorded on the surface of these CD-RWs with a felt-tipped pen, by ink-jet recording or a thermal transfer recording method as in CD-Rs, such indexes or design patterns cannot be conveniently changed when the stored data is changed. In this case, the stored data can be inconsistent with the indexes and design patterns printed on the surface of the CD-RWs and hence the contents of the stored data cannot be easily recognized by the indexes and design patterns. When a thin label such as used in CD-Rs is applied onto these CD-RWs, and later the label is replaced with another label in accordance with changes of the stored data, the media may be scratched or otherwise damaged.
SUMMARY
The product and process disclosed in this patent specification take into account the above-discussed problems and address and solve the above-discussed and other problems. Preferred embodiments provide an optical data storage medium capable of reversibly displaying information and a process of recording information that a user can read, by which a description for stored data in the medium can be visually recognized and the description can be readily recorded, erased or rewritten, without damaging the medium.
According to a preferred embodiment, an optical data storage medium (hereinafter may be briefly referred to as “medium”) includes a substrate, an optical data storage layer overlaid on the substrate and a reversible image recording layer overlaid on the optical data storage layer. Information is recorded in the reversible image recording layer so as to be visually recognizable.
The reversible image recording layer may preferably be thermosensitive and change its transparency and/or color in response to heat.
The substrate in the above medium may include a resin and the glass transition temperature Tg of the resin and a recording temperature Tr of the reversible image recording layer may have the following relationship:
Tr≦1.6×Tg (1)
wherein Tr is the recording temperature (° C.) of the reversible image recording layer, and Tg is the glass transition temperature (° C.) of the resin.
The glass transition temperature Tg of the substrate and the recording temperature Tr of the reversible image recording layer may have the following relationship:
Tr≦1.3×Tg×{(Lr+Ld)/(Lr+0.8×Ld)} (2)
wherein Tr is the recording temperature (° C.) of the reversible image recording layer, Tg is the glass transition temperature (° C.) of the substrate, Lr is the thickness (&mgr;m) of the reversible image recording layer, and Ld is the distance (&mgr;m) from a face of the substrate facing the reversible image recording layer to a face of the reversible image recording layer facing the substrate.
The recording temperature Tr of the reversible image recording layer in the medium may preferably be equal to or higher than about 120° C.
The reversible image recording layer in the medium may include a matrix resin and a low-molecular-weight organic substance dispersed in the matrix resin and reversibly change its transparency in response to heat.
In the above medium, the low-molecular-weight organic substance may include a low-molecular-weight organic substance having a melting point equal to or higher than about 100° C. and equal to or lower than 1.6 times the glass transition temperature Tg of the substrate.
The low-molecular-weight organic substance may include at least two low-molecular-weight organic substances, the melting points of which differ from each other by at least about 30° C.
The reversible image recording layer in the medium may include an electron donating color-displaying compound and an electron accepting compound which colors the electron donating color-displaying compound.
In the medium mentioned immediately above, the electron donating compound may include an electron donating compound having a melting point equal to or higher than about 120° C. and equal to or lower than 1.6 times the glass transition temperature Tg of the substrate.
The substrate in the medium may have a glass transition temperature Tg ranging from about 100° C. to about 180° C.
The medium may have a warping angle equal to or less than &p
Aihara Kenichi
Hattori Kyohji
Hotta Yoshihiko
Iwasaki Hiroko
Mishima Naoshi
Cooper & Dunham LLP
Evans Elizabeth
Ricoh & Company, Ltd.
LandOfFree
Optical data storage medium capable of reversibly displaying... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical data storage medium capable of reversibly displaying..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical data storage medium capable of reversibly displaying... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2576126