Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-04-12
2004-06-01
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S945000, C430S019000, C526S072000, C526S312000, C526S321000
Reexamination Certificate
active
06743567
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laser-sensitive polymer for data storage, a data storage media coated by the same, and a data storage device and method using the data storage media. In particular, the present invention relates to a polymer for data storage comprising two of the functional group of disperse red 1, which is a photoresponsive organic dye, bonded to a branched chain per every repeat unit, a data storage media coated by the same, a reversible and optical data storage device containing a thin film, and a data storage method using the device.
2. Description of the Related Art
In general, an optical data storage method involves a data storage media consisting of short wave-length laser and organic dyes sensitive to the same, of which method has a benefit of high density data storage. Taking advantage of properties of the organic dyes, e.g. easy structural transformation and an excellent processability for manufacturing thin films, the inventors discovered a reversible and optical data storage method using a data storage media for which the organic dyes or optical polymers containing the dye compounds as a substituent is applied. (Refer to U.S. Pat. Nos. 5,262,081, 5,445,853, 5,296,321, 4,666,819 and 5,384,221, German Patent No. 3623395, British Patent No. GB 2. 146787A, and Japanese Laid-Open Publication 1-294791.)
The basic principle of a reversible data storage method capable of data record-erase-read-rewrite is that when laser is irradiated to a data storage media containing organic dyes, the dyes go through color changes, birefringence changes and phase transition (e.g. crystal form
amorphous form or isotropic form
anisotropic form), depending on molecular structures thereof.
Well-known organic dyes for the technology described above include cyanine, phthalocyanine, squarilium, dithiol metal complex salt, quinone, spiropyran and azobenzene, and so forth.
The similarity in the molecular structure of each compound listed above is that each compound contains a different polar group that causes dipole moment. Thus, when a data storage media coated with one of the compounds above is irradiated by a polarized light with a particular wave-length, the molecules are arranged perpendicular to the plane of polarization of the irradiated light, which is basically due to the attractive force between dipole moments in a polar group. In this way, the newly arranged molecules go through the three optical changes aforementioned, and using this principle, data can be recorded in a data storage media.
The organic dyes applied to a data storage media, depending on a polar group's molecular structure, absorb ultraviolet or infrared having a wavelength 300 nm to 800 nm. Therefore, in order to develop an appropriate data storage element, it is important to choose a light source with particular wavelengths that causes optical changes in the data storage media.
Typically used light source for an optical data storage is a laser like Ga/As, He—Ne, Ar ion, Nd/YAG or He—Cd, having a wave-length of 780 nm, 630 nm, 488 nm, 514 nm, 360 nm or 325 nm.
However as for Compact disc (CD) or Laser disc (LD), for which an optical data storage media is applied, only 780 nm Ga/As and 630 nm He—Ne have been commercially used as a minor light source for a disc drive. Unfortunately, when these lights with longer than 600 nm wavelength are used as a recording light source for an optical data storage device, since the lights oscillate relatively long infrared, data storage density gets decreased thereby.
This problem occurs typically during the process of recording data, if an organic dye compound containing thin film is irradiated by polarized recording light having long wave length, the irradiation area of a data storage media is enlarged as compared with a short wave length light source. Therefore by using Ar ion laser of which wave length is below 520 nm as a recording light source, the area of a data storage media becomes small and data storage density per unit area is increased.
Attempts to increase data storage density as described above have been made by developing a polymer in which a functional group of azobenzene base organic dye compound is bonded to a branched chain, which is sensitive to a short wave length in a range from 300 nm to 400 nm. Thus, the inventors researched on the applications of a reversible and optical data storage media to the above polymer compound and were granted a patent in Korea (Korean Patent No. 77801, Application filing date: Feb. 27, 1991), and in relation to this, another application (Korean Patent Application No. 40216, Filing date: Aug. 22, 1997) was already laid open.
The basic mechanism behind the above technology is that a polymer having azobenzene base compound bonded to a branched chain coated a substrate to manufacture a thin film, and low output polarized ultraviolet was irradiated to the thin film. In result, it was possible to record data in high density with excellent resolution and new data could be rewritten after easing the previous data.
The media described above showed much improved resolution and recording speed by hundreds of nanosecond) as compared to those of prior art (U.S. Pat. No. 5,173,381) and German Patent No. 3,623,395: U.S. Pat. No. 4,837,745 and Japanese Publication No. 63-87626).
The pulse laser was observed as very beneficial not only that it was based on the molecular structure of a polymer compound employed, but also that it made it possible to record high density data at a speed of hundreds of nanosecond faster than others by using Nd/YAG pulse laser as a recording light, which usually oscillate a ultraviolet with 365 nm within 10 nanosecond.
Despite the benefits described above, because the short wave length pulse laser uses inorganic single crystal, thus making it expensive and big, it is considered rather inappropriate oscillation material for a compact sized data storage device.
Therefore, attempts to solve the cost and size problems, by applying Ar ion laser of which wave length can be modulated and is not expensive, have been made active for applying to a compact data storage device.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a polymer compound for data storage.
Another object of the present invention is to provide a data storage media using a substrate coated with such polymer.
Still another object of the present invention is to provide a data storage device for data write/read into such data storage media and a data storage method thereof.
To achieve the above object, there is provided 5 polymers for data storage: a polymer in which two of the disperse red 1 functional group, which is illustrated in Chemical formula 1, are bonded to a branched chain per each repeat unit, and four other polymers which are illustrated in Chemical Formulas, 2 to 5, respectively.
wherein n is a integer; m is 2, 4, 6, 8 or 10; R is the disperse red 1 functional group;
and the average molecular weight of the polymer is in the range of from about 2,000 to 15,000.
wherein n is an integer; two —CH
2
— are bonded to a benzene ring in orto-, meta- or para-position in the above
R is the disperse red 1 functional group
and the average molecular weight of the polymer is in the range of from about 2,000 to 15,000.
wherein n is an integer; R is
and the average molecular weight of the polymer is in the range of from about 2,000 to 15,000.
wherein R is
the ratio of X:Y is 3~97 mol %: 97~3 mol % and the average molecular weight of the polymer is in the rage of from about 2,000 to 15,000.
Preferably, the average molecular weight of the polymers which are illustrated in Chemical Formulas 2 to 5 is in the range of from about 3,000 to 10,000, respectively.
In addition, preferred ratio of X:Y in the polymer of Chemical Formula 5 is 5~30 mol %: 95~70 mol %.
The present invention provides a blend copolymer for data storage, which is prepared by mixing one of the polymers illustrated in Chemical Formulas 2 to 5 to either polymethylmetacrylate or polyvi
Han Yang Kyoo
Hong Ki Myung
Kim Bong Cheol
Kim Jin Hong
Ko Bong Soo
Angebranndt Martin
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
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