JPH04355226A - Rom and ram coexistence type optical recording medium and production thereof - Google Patents

Abstract

PURPOSE:To facilitate mass production as the information of a ROM region and the information for position detection of a RAM region can be reproduced by molding which utilizes the transition of a fixed phase and to allow not only DRAW but rewriting by erasing in the RAM region by utilizing the transition of a reversible phase. CONSTITUTION:A metallic mold 3 for molding which is formed with the reading out information signals of the ROM region and the information signals for position detection of the RAM region and the optical recording medium consisting of a recording layer 2 of a high-polymer elastomer having the reversible phase which reversibly repeats hardening and softening at room temp. or above and the fixed phase which fixes the positional relation of the resin particles are disposed to face each other. The optical recording medium is so produced that the recording medium can be molded in the state of the softening temp. of the fixed phase of the recording layer 2 or above.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ROM/RAM mixed optical recording medium in which recording is performed by elevating the recording layer by irradiation with light, and a method for manufacturing the same.

0002

[Prior Art] Recently, R
In addition to OM (read-only) optical discs (e.g. compact discs, video discs), RAM (writable) such as write-once optical discs and rewritable optical discs.
The development of optical discs is active. As a write-once optical disc, there is a perforation method in which recording is performed by irradiating a laser beam onto a disc substrate and perforating the disc substrate. For rewritable optical discs, a perpendicularly magnetized film is formed on the disc substrate, and information is recorded by irradiating this magnetized film with a laser beam and reversing the direction of magnetization at the irradiated point. During playback, information is recorded using the Kerr effect. There are a magneto-optical method that detects the rotation of the plane of polarization, and a phase change method that uses a substrate to form a recording layer that reversibly changes between a crystalline state and an amorphous state.

On the other hand, in order to take advantage of the characteristics of optical discs with large recording capacities, ROM (read-only) areas and RAM (
ROM/RAM mixed type optical discs, in which writeable (writeable) areas are mixed on one optical disc, are being actively developed.

0004

[Problem to be Solved by the Invention] When a ROM/RAM mixed type optical disk is configured using a hole punching type optical disk,
Since the ROM area can be produced by molding, replication production is easy. However, although it is possible to add data to the RAM area,
It has the disadvantage that it cannot be erased and rewritten. Also, RAM
In order to create a perforated optical disc with a region using an organic dye-based material, an information signal for position detection of the RAM region (
tracking guide groove or wobbling pit)
Since it is necessary to spin-coat a recording layer on a substrate having an uneven surface, it is not easy to mass-produce uniform, high-quality optical disks.

[0005] Magneto-optical or phase-change optical discs,
When configuring a ROM/RAM mixed optical disk, RAM
The area can be erased and rewritten. However, since the ROM area cannot be produced by molding, there is a drawback that copy production is not easy.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a polymer having a reversible phase that reversibly repeats hardening and softening at or above room temperature and a stationary phase that fixes the positional relationship of resin molecules. ROM/R is an optical recording medium consisting of an elastomer recording layer, in which a read-only ROM area and a writable RAM area are formed on the same recording layer.
This provides an AM mixed optical recording medium.

[0007] Furthermore, a molding die in which a readout information signal for the ROM area and an information signal for detecting the position of the RAM area are formed, a reversible phase that repeats hardening and softening reversibly above room temperature, and a position of the resin molecules. A ROM/RAM mixed type in which an optical recording medium consisting of a recording layer of a polymer elastomer having a stationary phase that fixes the relationship is opposed and molded at a temperature equal to or higher than the softening temperature of the stationary phase of the recording layer. A method for manufacturing an optical recording medium is provided.

According to the ROM/RAM mixed optical recording medium configured as described above and its manufacturing method, a fixed phase transition and a reversible phase transition are utilized, that is, a fixed phase transition is utilized. Since the information in the ROM area and the information for position detection in the RAM area can be replicated by molding, mass production is easy.Moreover, by using reversible phase transition, the RAM area can not only be added to, but also erased and replayed. You can also write.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a ROM/RAM mixed optical recording medium (hereinafter referred to as an optical recording medium) and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings. First, the optical recording medium (base body) before molding will be explained. FIG. 3 is a sectional view showing the optical recording medium before molding. In the figure, 1 is a substrate. The substrate 1 is a transparent substrate made of plastic (a plate or film of polycarbonate, acrylic, epoxy, polyolefin, etc.), glass, etc. used in optical disks and optical cards.

Reference numeral 2 denotes a recording layer, which is formed by a coating method. The recording layer 2 is composed of a polymer elastomer and a light absorber. This polymer elastomer has a reversible phase in the polymer chain that has a state change function that repeats reversible hardening and softening.
It consists of a stationary phase with fixed points that fix the positional relationship of the polymers.

[0011] The properties necessary for the reversible phase are that the elastic modulus changes greatly in response to temperature changes, and that it also has a clear threshold value, so that the glass transition point or crystal melting point that exists at a temperature appropriate for the purpose is Make use of it. If the transition point T1 of the reversible phase is too low, the recording may be erased even at room temperature or changed by the reproduction light. Conversely, if it is high, the recording sensitivity will be low. On the other hand, the stationary phase utilizes chemically and physically formed fixing points such as crosslinking, crystallization, aggregation, and hydrogen bonding of polymer chains. The softening temperature T2 of the stationary phase must be higher than the transition point of the reversible phase, and higher temperatures are better at remembering the original shape.

[0012] Examples of the polymer elastomer include polyurethane, transpolyisoprene, polynorbornene,
Styrene-butadiene copolymer and radiation crosslinked polyethylene are used. Furthermore, by selecting a polymer whose elastic modulus changes at a temperature appropriate for the purpose as the reversible phase and introducing a fixed point therein, it is possible in principle to use a wide variety of resins. Either thermoplastic elastomer or thermosetting elastomer may be used.

[0013] Further, a light absorbing agent that absorbs recording light and increases the temperature of the recording layer 2 is mixed in the polymer elastomer. The light absorbing agent is selected from inorganic pigments, organic pigments, organic dyes, metal fine particles, and the like having the ability to absorb laser beams, and is dispersed or dissolved in the polymer elastomer.

Examples of the light absorbent include inorganic pigments such as carbon black, cobalt blue, cobalt green, and viridian, organic pigments such as azo pigments, indanthrene, thioindigo, perylene, dioxazine, and phthalocyanine, cyanines, pyryliums, Squarylium,
Organic compounds such as croconiums, azulenes, pentamethines, thioindigos, anthraquinones, naphthoquinones, phthalocyanines, naphthalocyanines, porphyrins, tetrahydrocholines, dithiols, diamines, indoanilines, dioxazines, dithiazines, etc. Dye, Au, Ag, Cu, Te, Se, In, Sn, A
l, Si, Ge, Pb, Bi, Zn, Ni, Pt, Co
, Cr, and other metal particles.

[0015] Further, as a coating method for the recording layer 2 in the optical recording medium, a spin coating method, a spray method, a dipping method, a blade coating method, etc. can be used. The thickness of the recording layer 2 is in the range of 10 to 5000 nm, preferably in the range of 100 to 2000 nm. Note that a buffer layer for absorbing shape deformation may be provided on the recording layer 2, if necessary, and a reflective layer and a protective layer may also be provided. A base layer may be provided if necessary.

Next, the principle of recording, reproducing, and erasing on the optical recording medium (element body) shown in FIG. 3 will be explained. FIG. 4 is a diagram showing the principle of recording, reproducing, and erasing on an optical recording medium. (Principle of Recording) The polymer elastomer of the recording layer 2 is heated to a temperature higher than the transition point of the reversible phase (T2 > T > T1) to cause deformation. When irradiated with a laser beam for recording, the light absorbent absorbs the laser beam and generates heat, and the reversible phase is heated, softens, and expands. When the laser beam is cut off, the recording layer cools down immediately, and the ridges created by thermal expansion are rapidly cooled down.
It returns to room temperature while maintaining its deformation. This is because the motion of the polymer chains is restricted below the transition point T1 of the reversible phase, and the deformation is frozen.

(Principle of Reproduction) Reproduction is performed by irradiating a recording mark with a laser beam of low power that does not raise the temperature above the transition point T1 of the reversible phase so as not to relax the deformation, and to absorb the light that is reflected back. Detect intensity.

(Principle of erasing) This deformed recording layer is heated again to a temperature above the transition point T1 of the reversible phase where molecular motion is possible,
When slowly cooled, the deformation is released to eliminate residual internal stress and the stationary phase recovers to its original memorized shape. If the recording layer is heated above the softening temperature T2 of the stationary phase, the initially fixed shape will be re-memorized into a new shape. Heating the recording layer above (T2 > T > T
1) It is necessary to do so.

Next, a method for manufacturing a ROM/RAM mixed type optical recording medium will be explained. 1(A) to 1(C) show the manufacturing process of an optical recording medium. FIG. 1(A) is a diagram showing the state before molding, FIG. 1(B) is a diagram showing the molding state, and FIG.
) is a diagram showing a molded optical recording medium. Also, Figure 2
1 is a perspective view of an optical recording medium on which a readout information signal for a ROM area and an information signal for position detection (tracking signal) for a RAM area are formed; FIG.

A recording layer 2 is coated and formed on a substrate 1, and a readout information signal of the ROM area and an information signal for position detection of the RAM area (tracking guide groove or wobbling A molding die 3 in which pits, sector signals, etc.) are engraved is placed opposite to the molding die 3. [See FIG. 1(A)]. Then, the above information is molded and transferred to the recording layer 2 by pressing the molding die 3 against the recording layer 2 of the element body of the optical recording medium. During this molding, the reversible phase and stationary phase are heated to a temperature equal to or higher than the softening temperature T2 (T>T2), and then the mold 3 (stamper) is applied to cool the reversible phase and stationary phase (T<T1) [Figure 1 See (B)]. Thus ROM
A ROM/RAM mixed optical recording medium as shown in FIG. 2 is obtained in which area information, an information signal tracking signal for detecting the position of the RAM area, a sector signal, etc. are recorded [FIG. 1
(C)].

Recording by molding utilizing this stationary phase transition will not be erased unless the recording layer is heated to T2 or higher again. Irregularities are formed on the surface of the ROM area of the recording layer 2,
Information can be read out by detecting the amount of return light of the playback light, similar to the playback method for normal optical discs and optical cards. Guide grooves or wobbling pits for tracking are formed on the surface of the RAM area of the recording layer 2, and recording, reproduction, and erasing can be performed using a recording laser beam according to the principle shown in FIG. 5 described above.

As described above, according to the present manufacturing method, since the information in the ROM area and the information signal for detecting the position of the RAM area are copied by molding transfer, it is extremely easy to copy the ROM/RA information.
M-mixed optical recording media can be produced. Moreover, this ROM・
Since the RAM mixed optical recording medium is an optical recording medium consisting of a recording layer made of a polymer elastomer having a reversible phase and a stationary phase, it is possible not only to add data to the RAM area but also to erase and rewrite data in the RAM area.

Therefore, the present ROM/RAM mixed optical recording medium is easy to reproduce, can be manufactured in large quantities, and is suitable for audio and
Suitable for video software, game software, electronic publishing, membership cards, credit cards, etc. In addition, this ROM
- The RAM-mixed optical recording medium may be in any form, such as a disc-shaped optical disk, a plate-shaped optical card, or a long optical tape.

Furthermore, since the present ROM/RAM mixed optical recording medium can form the recording layer 2 by coating, it can be easily manufactured using relatively inexpensive equipment. Furthermore, a recording layer 2 is placed on a flat substrate 1 that does not have information signals (guide grooves or wobbling pits for tracking) for detecting the position of the RAM area.
Since the discs are formed in advance, it is easy to mass-produce uniform, high-quality optical discs.

[0025]

[Effects of the Invention] As detailed above, the RO according to the present invention
An M/RAM mixed optical recording medium is an optical recording medium consisting of a recording layer of a polymer elastomer having a reversible phase that repeats hardening and softening reversibly above room temperature and a stationary phase that fixes the positional relationship of resin molecules. Since the read-only ROM area and the writable RAM area are formed on the same recording layer, the R
The AM area can be erased and rewritten as well as additional writing, and furthermore, the method for manufacturing a ROM/RAM mixed optical recording medium according to the present invention provides readout information signals in the ROM area and position detection signals in the RAM area. A recording layer made of a polymer elastomer that has a reversible phase that reversibly repeats hardening and softening above room temperature and a stationary phase that fixes the positional relationship of resin molecules. Since the molding is performed with the recording medium facing the recording layer at a temperature higher than the softening temperature of the stationary phase of the recording layer, information in the ROM area and information in the RAM area are transferred by mold transfer using the transition of the stationary phase. Since the information signal for position detection is copied, ROM/RAM mixed type optical recording media can be mass-produced extremely easily. In this way, a ROMRAM mixed optical recording medium with high marketability is provided.

[Brief explanation of the drawing]

[Fig. 1] (A) to (C) show the manufacturing process of a ROM/RAM mixed optical recording medium, where (A) shows the state before molding, and Fig. 1 (B) shows the molded state. The figure shown in FIG. 1C is a diagram showing a molded ROM/RAM mixed type optical recording medium.

FIG. 2 is a perspective view of a ROM/RAM mixed optical recording medium in which a readout information signal for a ROM area and an information signal for position detection (tracking signal) for a RAM area are formed.

FIG. 3 is a diagram showing an optical recording medium (base body) before molding.

FIG. 4 is a diagram showing the principle of recording, reproducing, and erasing on an optical recording medium.

[Explanation of symbols]

1 Board 2 Recording layer 3 Mold 4 Optical recording medium 5. Light absorber T1 Reversible phase transition temperature T2　　Transition temperature of stationary phase

Claims (2)

[Claims] [Claim 1] An optical recording medium comprising a recording layer of a polymer elastomer having a reversible phase that reversibly repeats hardening and softening at or above room temperature and a stationary phase that fixes the positional relationship of resin molecules, the optical recording medium being read-only. A ROM/RAM mixed optical recording medium characterized in that a ROM area and a writable RAM area are formed on the same recording layer. [Claim 2] A molding die in which a readout information signal for the ROM area and an information signal for detecting the position of the RAM area are formed, a reversible phase that reversibly repeats hardening and softening above room temperature, and the position of resin molecules. An optical recording medium consisting of a recording layer of a polymer elastomer having a stationary phase that fixes the relationship is placed facing each other and molded at a temperature equal to or higher than the softening temperature of the stationary phase of the recording layer. A method for manufacturing a ROM/RAM mixed optical recording medium.