JP2000311387A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold visible information with which alteration and forgery are extremely difficult by constituting the visible information which is disposed in a non-data recording region and is visually recognizable by prepits disposed at a substrate. SOLUTION: The visible information which is recognizable when an optical card is viewed from an incident direction of a light beam for recording reproduction is formed in the non-data recording region. This visible information is composed of the prepits formed at the transparent substrate. The prepits constituting the visible information are formed in land parts 303 between the tracking grooves of the transparent substrate and the visible information is formed by ways of arraying these pits 301. The shapes and sizes of the pits 301 to be disposed in the land parts 301 may be properly set by the ease of viewing of the visible information, etc. When the forming positions of the pits are disposed in the non-recording and reproducing region existing at the end of the recording layer forming region of the optical card, the shape or size thereof or both thereof are preferably controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium for optically recording, reproducing, or recording and reproducing information. In particular, the present invention relates to an optical recording medium capable of preventing forgery, tampering, and alteration for ensuring security.

[0002]

2. Description of the Related Art In recent years, as society has become more computerized, as a means for efficiently handling a wide variety of information, as a card-shaped information recording medium having excellent portability, a prepaid card, a credit card, a bank card, an ID card, etc. Is used. The storage of information on these cards is mainly performed magnetically on a magnetic stripe provided on a normal card.
However, since magnetic information is easily falsified and the recording capacity is extremely limited, in recent years, an IC card in which an IC chip or the like is embedded or a card-shaped optical recording medium for optically recording information (hereinafter referred to as an “optical card”) ") Has been put into practical use, or put into practical use.

Information is recorded on an optical card by, for example, a change that occurs in the recording layer by irradiating the recording layer with a laser beam, such as a crystal-amorphous phase change, formation of pits (holes), and a magneto-optical effect. The change is performed by causing a change in the plane of polarization, and the information recorded in such a manner is detected by detecting the change caused in the optical recording layer using light. As described above, information recorded on an optical card cannot be visually recognized as meaningful information, and therefore, the recorded information is much more difficult to falsify than conventional magnetic information. Are better.

[0004] By the way, even in the case of a card-shaped medium of such a new recording system, the card must be issued by an authorized issuer, or similar to the conventional card-shaped information medium. There is a strong demand for providing information indicating that the card owner is the true owner or the like to the card-shaped medium as visible information. Considering the current usage of card-shaped media, which may perform personal authentication using only this visible information, it is one of the most important technical issues to prevent forgery and falsification of this visible information as much as possible. is there.

[0005] Many techniques have been proposed to make it difficult to forge or falsify such visible information. For example, Japanese Patent Application Laid-Open No. 55-146795 discloses a certification card or the like in which an insertion card is covered with a transparent cover sheet, and visible information is recorded on the surface of the insertion card by laser through the transparent cover sheet. I have.

A method for arranging a hologram image on a card-like optical information recording medium, as described in Japanese Utility Model Laid-Open Publication No. Sho 62-191465,
Japanese Patent Publication No. 98 discloses a method in which visible image information is previously provided on a card, such as a method in which minute characters and patterns are attached to a card having an IC chip, magnetic recording, or optical information recording. Also, to increase security,
As a method for providing various information together with an optical information recording medium, Japanese Patent Laid-Open No. Hei 10-329460 discloses a method for recording an image visualized by recording pits.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such background art, and has as its object to provide an optical recording medium which holds visible information which is extremely difficult to falsify or forge. It is assumed that.

[0008]

An optical recording medium which can achieve the above-mentioned object is an optical recording medium having a substrate having a tracking groove on a surface thereof and an optical recording layer covering a predetermined region of the surface of the substrate. A recording medium, wherein the predetermined area includes a data recording area and a non-data recording area, the non-data recording area includes visible information that can be visually recognized, and the visible information is provided by pre-pits provided on the substrate. It is characterized by comprising.

By adopting such a configuration, when the visual information of the completed optical recording medium is to be tampered with, there is a high possibility that the function of the optical recording medium itself is impaired. In the case of performing additional processing, the history of tampering remains in the optical recording layer. Therefore, the forger makes unauthorized changes to the visible information on the optical recording medium,
The danger of successfully producing altered or forged optical recording media is extremely low.

[0010]

An optical card according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of the optical card 100, and FIG. 2 is a schematic plan view of the optical card of FIG. FIG. 1 is a sectional view taken along the line BB of FIG. In FIG. 1, reference numeral 102 denotes a transparent substrate,
103 is an optical recording layer, 104 is an adhesive layer, 105 is a protective substrate, 106 is a recording / reproducing light beam 1 of the transparent substrate 102.
A hard coat layer 108 for preventing scratches and dirt from adhering to the incident surface 07 is a printing layer carrying visible information that can be recognized when the optical card is visually observed from the direction of arrow A, for example. It is. Reference numeral 110 denotes a tracking groove provided on the substrate for guiding a recording / reproducing light beam.
In FIG. 2, reference numeral 200 denotes a planar spread (recording layer formation region) of the optical recording layer 103, and reference numeral 202 denotes an area (data) in which data or the like is recorded or data to be read by a laser beam is recorded. Recording area)
And the recording / reproducing area 20 of the recording layer forming area 200
The area other than 2 is the non-data recording area 204. 206
Is visible information formed in the non-data recording area 204 and recognizable when the optical card is visually observed from a direction in which a light beam for recording and reproduction is incident. The visible information 206 is composed of pre-pits formed on the transparent substrate 102. The visible information 206 will be described in more detail with reference to FIG. 3 which is an enlarged view of the portion and FIG. 4 which is a sectional view taken along the line CC in FIG.

FIG. 3 is an enlarged plan view of the visible information 206 shown in FIG. 2, and FIG. 4 is a sectional view taken along the line CC of FIG. 3 and 4
In the figure, reference numeral 301 denotes pits constituting the visible information 206. The pit 301 is formed in an area 303 (hereinafter referred to as a "land portion") between the tracking grooves 110 of the transparent substrate 102. 2
06 is formed.

The pit 30 provided in the land 303
The shape and size of 1 may be appropriately set depending on the visibility of the visible information 206 and the like. For example, the visible information 206 may be configured by pits having a shape as shown in FIG. For example, when the visible information 206 is formed by pits, the depth of the pits is preferably, for example, 0.05 to 1 μm in order to obtain a good visible image.

(About the pit formation position) When the visible information 206 is provided in the non-recording / reproduction area 206 located at the end of the recording layer formation area 200 of the optical card as shown in FIG. It is preferable to control the shape, size, or both. That is, at the end of the recording layer forming area of the optical card, data is not recorded on the land, or information to be read by the laser beam does not exist on the land, but it is located on the non-recording / reproducing area. Even so, the tracking groove 110 functions as a tracking groove that allows the recording / reproducing light beam 107 to follow a desired track and access the desired track. FIG. 6 is an explanatory diagram of an example of a tracking method of the recording / reproducing light beam 107. That is, the sub-beam spots 601-1 and 601-2 are radiated so as to straddle the tracking groove 110, and by detecting the difference in the reflected light intensity of each sub-beam, the tracking formed on the transparent substrate at a predetermined pitch. The recording / reproducing light beam 10 is positioned at the center of the land portion 303 sandwiched by the grooves 110.
The control is performed such that the seven spots 602 are always located.

Here, when the pits constituting the visible information 206 are formed in the area irradiated by the sub beam, there is a possibility that the tracking of the recording / reproducing light beam in the non-recording / reproducing area may be affected. Therefore, FIG.
In the case where visible information constituted by pits is provided in a non-recording / reproducing area as shown in FIG.
01 is preferably provided at a position on the land portion 303 where the sub beam is not irradiated. The specific positions are the spot size of the sub beam and the tracking groove 1.
Since it changes depending on the width of the land portion 10 or the like, it cannot be specified unconditionally. For example, as shown in FIG. 6, the center portion of the land portion 303, specifically, the center line 603 of the land portion, 5 to 95% of the width, especially 30 to 65%
When the pits for the visible information 206 are formed in the region 605 having a width of, the visibility of the visible information is not impaired, and the tracking is not substantially affected. .

The size of the pit in the track parallel direction is not particularly limited as long as it is within the non-data recording area.
The pit may have a different pit length, a repetition of a different shape, or a long pit shape extending over several cm.

The visible information 20 according to the above-described embodiment
As a method of forming the pits for 6, a tracking groove,
As with the pre-pits and the like provided in the recording / reproducing area, there is a method of providing the stamper at the same time as the stamper is created. According to this method, the visible information is recorded at the same time as the molding of the substrate, and the cost of the optical card with visible information can be reduced.

The pit 301 for the visible information 206 has been described as a pit 301 as a physical concave portion provided on the substrate in the above-described embodiment, but the pit 301 for the visible information 206 is replaced with the pit 301 in the present invention. The present invention is not limited thereto, and any method can be used as long as the difference in the reflected light intensity between the land and the pit can be obtained. For example, any of the conventional pre-groove forming methods can be used. For example, a method of obtaining a difference in reflection intensity between a land portion and a pit portion by a pit, a groove, or a rough surface shape, a method using a difference in reflected light intensity due to a crystal-amorphous phase change, a change in a polarization plane due to a magneto-optical effect And a method using a change in reflected light intensity.

(Multiple Row Pits) FIG. 7 is an enlarged plan view of the visible information 206 of another embodiment of the optical card according to the present invention, and FIG. 8 is a sectional view taken along the line DD in FIG. As is clear from FIGS. 7 and 8, the pit 3 for the visible information 206
01 are formed on the land portion 303 in a plurality of rows in the width direction. With such a configuration, the contrast difference between the land portion and the pit portion is large, and it can be recognized as clear information that can be recognized more clearly. Also in this embodiment, the pit 301 has the area 605 at the center of the land 303 as described in the first embodiment so as not to affect the tracking by the sub-beam.
It is preferable to provide it inside.

Also in this configuration, the shape of the pits and the like are not particularly limited. For example, the size of the pit in the track parallel direction is not particularly limited as long as it is within the non-data recording area. It may be a repetition of micron pits, a different pit length, a repetition of a different shape, or a long pit shape extending over several cm. Specifically, for example, the pits may be shaped as shown in FIG.

Next, each member constituting the information recording medium will be described.

As the transparent substrate, any substrate can be used as long as it has good transparency and can be optically recorded and reproduced, and a glass plate or a plastic resin such as polycarbonate, polyvinyl chloride, polymethyl methacrylate, and polyethylene terephthalate can be used. No.

As the recording layer, any material can be used as long as recording and reproduction and erasing can be performed by a laser beam, and an organic dye-based recording material and a metal-based recording material can be used. Further, there may be other functional layers such as a reflective layer and an undercoat layer.

As the protective substrate, the optical recording layer is physically and
A material that is chemically protected is preferable, and for example, a plastic, a glass plate, a metal, ceramics, paper, or a composite material thereof can be used.

The material of the hard coat layer is an optically transparent protective layer having a high abrasion resistance for protecting the surface of the front substrate from scratches, dusts, etc. Specifically, urethane acrylate, unsaturated polyester, Examples thereof include an ultraviolet curable resin such as an epoxy acrylate, and a silicon-based thermosetting resin. Particularly, a urethane acrylate having high hardness is desirable.

As the adhesive layer, a conventionally known ordinary adhesive can be used. For example, polymers and copolymers of vinyl monomers such as vinyl acetate, acrylate, vinyl chloride, ethylene acrylic acid, and acrylamide; thermoplastic adhesives such as polyamide, polyester, and epoxy; amino resins (urea resins, melamine resins) Adhesives such as phenolic resin, epoxy resin, urethane resin and thermosetting vinyl resin, and rubber-based adhesives such as natural rubber, nitrile rubber, chloro rubber, and silicone rubber are used.

As the printing layer, in addition to the ordinary design printing, a printing receiving layer resin sheet for post printing, a magnetic stripe, a bar code, an OCR character, a hologram, a sign panel, etc. Things can be provided.

[0028]

The present invention will be described more specifically with reference to the following examples.

Example 1 An optical card 100 having the structure shown in FIGS. 1 and 2 was prepared as follows.

First, the transparent substrate 102 having the tracking grooves 110 and the pits 303 constituting the visible information 206
A stamper for molding was prepared by the following method. First, a master for molding an optical card substrate was prepared.

On a 5-inch square quartz glass substrate, a positive photoresist for i-line (trade name: THMR-iP310)
0; Tokyo Ohka Kogyo Co., Ltd.) was formed into a film having a thickness of 0.5 μm by spin coating, and prebaked at 80 ° C. for 90 seconds. Using a photomask, an exposure device (trade name: P
LA-500F; manufactured by Canon Inc.) and a mercury xenon short arc lamp (trade name: AHX) as a light source
D; manufactured by Oak Manufacturing Co., Ltd.). The exposure amount is i-line (3
65 m) at 30 mJ / cm ² , and the mask pattern dimensions are a groove width of 2.3 μm and a recording track width of 9.7.
μm and a pitch of 12 μm. Further, pits of 5 μm × 12 μm were provided in the non-data recording area so that the visible information 206 was formed in a repeating pattern.

Next, the photoresist was heated at 23 ° C. and 30 ° C. with a developing solution (trade name: NMD-3; manufactured by Tokyo Ohka Kogyo Co., Ltd.).
Spin development was performed under the condition of seconds. Next, post-baking was performed at 130-C for 20 minutes to obtain a master. Next, after a conductive film is sputtered on the master, electroforming is performed using the conductive film as an electrode to laminate an electroformed film, and then the electroformed film is peeled off together with the conductive film, and the stamper is removed. And

Next, thickness 0.4 mm, length 54 mm, width 85
The stamper obtained above is superimposed on a polycarbonate substrate (Panlite; Teijin Chemicals Ltd.) via a photopolymer resin, and the pattern of the stamper is transferred by irradiating UV light, and the tracking groove 110 and the visible light are visible. Transparent substrate 102 with pits 303 for information 206
I got

Next, a polymethine dye (1,1,5,5-tetrakis- (p-diethylaminophenyl) is added to the recording layer forming region 200 on the side of the transparent substrate 102 where the tracking grooves 110 and the pits 303 are formed. ) -2,4-Pentadienium perchlorate) and an azulenium salt compound (antimony fluoride salt of N, N, N, N-tetrakis- (p-di-methoxyethyl) -p-phenylene-aminium). A gravure coat of a 3.0 wt% diacetone alcohol solution containing a weight ratio of 1: 1 was performed, followed by drying to form a recording layer 103 having a thickness of 900 A on the transparent substrate 102.

Next, thickness 0.3 mm, length 54 mm, width 8
A protective substrate 105 was prepared by printing visible information 108 on a 5 mm polycarbonate substrate (trade name: Panlite; manufactured by Teijin Chemicals Limited). Next, the transparent substrate on which the optical recording layer was formed and the protective substrate were heated at 120 ° C. via a hot-melt type dry film adhesive 104 having a thickness of 50 μm (trade name: O-4121; manufactured by Crabeau). Pressed and bonded.

Finally, a hard coat agent (trade name: Unidick 17-824-9; manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the surface of the transparent substrate opposite to the recording layer, and
Hard coat layer 106 cured by V light and having a thickness of 10 μm
Was formed to manufacture the optical card 100.

Example 2 An optical card was manufactured in the same manner as in Example 1 except that the size of the pits constituting the visible information 206 was 3 μm × 3 μm.

Embodiment 3 As pits constituting the visible information 206, 2 μm × 1
An optical card was prepared in the same manner as in Example 1 except that a 2-micron pit repetition pattern was provided in two rows at a line interval of 1.7 microns.

Reference Example 1 Example 1 except that no pit indicating visible information was formed.
An optical card was created in the same manner as described above.

The visual information of each of the optical cards prepared in each of the above examples could be confirmed very clearly visually.
Further, the optical card of each of the above embodiments and Reference Example 1 was mounted on an optical card recording / reproducing apparatus (trade name: RW-50; manufactured by Canon Inc.), and a laser beam having a linear velocity of 5.5 m / sec was used.
The data was recorded in the data recording area and reproduced. As a result, no significant difference was found in the occurrence frequency of the tracking error between the optical card of Reference Example 1 in which the visible information was not provided in the non-data recording area. The spot diameter of the recording / reproducing light beam on the optical card surface of the optical card recording / reproducing apparatus is a circle of about 2.5 μm, and the spot diameter of the tracking sub-beam on the optical card is an ellipse of 2.7 × 5 μm. And the center of the elliptical spot of the sub-beam is located at the land where the spot of the recording / reproducing light beam is located, and the tracking is adjacent to the land. It was adjusted to be located at the boundary with the groove.

[0041]

As described above, according to the present invention, visible information can be provided without reducing the optical recording area of the information recording medium. Further, by forming the visible information on the substrate by using the pre-pits, it is possible to provide a highly secure information recording medium in which forgery, falsification, and alteration of the information recording medium are more difficult.

Further, when the pits constituting the visible information are arranged near the center of the land portion, the provision of the pits for the visible image in the land portion minimizes the influence on the tracking or minimizes the influence on the tracking. Can be substantially eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an information recording medium according to one embodiment of the present invention.

FIG. 2 is a schematic plan view of the information recording medium of FIG. 1 as viewed from the direction of arrow A.

FIG. 3 is an enlarged plan view of a visible information forming portion of the information recording medium of FIG. 2;

FIG. 4 is a sectional view taken along line CC of FIG. 3;

FIG. 5 is an explanatory diagram of another embodiment of visible information.

FIG. 6 is a schematic explanatory diagram of a region where pits constituting visible information are formed.

FIG. 7 is an explanatory diagram of another embodiment of visible information.

FIG. 8 is a sectional view taken along the line DD in FIG. 7;

FIG. 9 is an explanatory diagram of another embodiment of visible information.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 optical card 102 transparent substrate 103 optical recording layer 104 adhesive layer 105 protective substrate 106 hard coat layer 107 recording and reproducing light beam 108 printing layer 110 tracking groove 200 recording layer forming area 202 data recording area 204 non-data recording area 206 visible information 301 pit 303 land portion 601-1, 601-2 spot of sub beam 602 spot of recording and reproducing light beam 603 center line of land portion 605 pit forming area

Claims (7)

[Claims] 1. An optical recording medium having a substrate having a tracking groove on a surface thereof and an optical recording layer covering a predetermined area on the surface of the substrate, wherein the predetermined area is a data recording area and a non-data recording area. An optical recording medium, wherein the non-data recording area includes visible information that is visually recognizable, and the visible information is constituted by pre-pits provided on the substrate. 2. The optical recording medium according to claim 1, wherein the pre-pit is provided at a land portion between a plurality of grooves of the substrate. 3. The optical recording medium according to claim 2, wherein the pre-pit is located at a center of the land. 4. A plurality of pre-pits are provided on the land in a direction perpendicular to the groove.
The optical recording medium according to any one of the above. 5. The optical recording medium according to claim 1, wherein said optical recording medium is an optical card.
5. The optical recording medium according to any one of items 1 to 4, 6. The optical recording medium according to claim 1, wherein said optical recording layer has visible light transmittance. 7. The optical recording medium according to claim 1, wherein said optical recording layer is an organic dye recording layer.