Optical recording method having two degrees of reflectivity and

Details Optical recording method having two degrees of reflectivity and Optical recording method having two degrees of reflectivity and

1989-12-07

1992-08-11

Richardson, Robert L.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

235457, 283 86, 283 91, 902 25, G11B 700

Patent

active

051386046

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL APPLICATION FIELDS

The present invention relates to an optical recording medium capable of making an optical record of information and, more particularly, to optical recording media of such types as a read only memory (ROM) type for reading out information bits with laser beams, a direct read after write (DRAW) type capable of writing information with laser beams or an erasable or writable type and a process for making them.


BACKGROUND TECHNIQUES

Heretofore, magnetic recording materials have been primarily used as recording materials embedded in cards such as credit or bank cards. Such magnetic recording materials have the merit of being able to read and write information easily, but problems associated with them are that the information may be relatively easily falsified and high-density information recording is unachievable.
Recently, IC or optical cards are being under development with the recording and reproduction of high-density information in mind. In particular, optical cards relying upon optical recording/reproduction systems have an advantage of recording information at much higher densities over those to which conventional magnetic or IC systems are applied.
In this connection, the optical recording media or materials so far proposed for optical cards involve the following.
The recording medium shown in FIG. 19(A) as an example is a so-called ROM (read only memory) type of optical recording medium. In this instance, an optical card 50 is provided thereon with an optical recording medium comprising a portion 50 of high reflectivity and a portion 52 of low reflectivity, said portion 52 of low reflectivity defining an information recording bit.
FIG. 19(B) is a sectional view of the optical card 50. As illustrated, a transparent substrate 54 is provided thereon with a light reflecting material 55 corresponding to an information recording pattern by photolithography, while a substrate material 58 having a black printed layer 57 thereon is joined thereto through an adhesive layer 56, thereby forming the optical card 50. In this instance, therefore, the information is read out by detecting a difference in the light reflectivity between the light-reflecting material 55 and the printed layer 57.
FIG. 20 shows an example of the ROM type of optical recording medium disclosed in Japanese Patent Publication No. 58-48357. In this instance, a film 60 of a silver halogenide emulsion formed on a certain substrate material is subjected to pattern exposure corresponding to the information to be recorded and the developed, thereby forming an information recording bit 62 differing in light reflectivity from a surrounding portion 61.
FIG. 21 illustrates an example of the so-called DRAW (direct read after write) type of optical recording medium wherein no development treatment is needed after information has been written and the information can thus be read directly after writing. In this instance, a photopolymer 71 is formed on its one side into an irregular or modulated plane, along which an optical recording material 72 such as Te is provided in the form of a thin film. That film is bonded to a substrate 74 with a bonding agent 73, and a light transmitting acrylic resin 75 or the like is then laminated on the upper side of the photopolymer 71, thereby forming an optical recording medium.
Writing of information on such an optical recording medium may be achieved by scanning the modulated plane of the recording medium with a laser beam, 76 irradiated as illustrated in FIG. 22 to ensure that e.g., the convex portions are in alignment therewith and, thereafter, writing bit information on the convex portions.
FIG. 23 illustrates a DRAW type of optical recording medium disclosed in Japanese Patent Publication No. 58-48357. In this instance, a film 80 of a silver halogenide emulsion is formed on a substrate and then subjected to pattern exposure and development, thereby forming portions 81 and 82 different in light reflectivity from each other. After the position of the portion 81 has been ascertained by a d

REFERENCES:
patent: 4014602 (1977-03-01), Ruell
patent: 4501439 (1985-02-01), Antes
patent: 4641017 (1987-02-01), Lopata
patent: 4945215 (1990-07-01), Fukushima et al.

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