JPS6325850A - Optical recording disk - Google Patents

Abstract

PURPOSE:To reduce a tracking error and make an optical recording disk thin by providing projecting stripes, which form partition walls of tracking grooves on the recording layer forming face of a first substrate, with base parts and projecting parts which are provided in about center of base parts and are narrower than base parts. CONSTITUTION:First disc-shaped substrates 31 and 35, and tracking grooves 41 and 45 are formed on substrates 31 and 35, and recording layers 71 and 75 are formed on these groove forming faces, and the first substrates 31 and 35 are joined with a second disk-shaped substrate 6 integrally so that recording layers 71 and 75 are enclosed. In this case, projecting stripes 51 and 55 which form partition walls of tracking grooves 41 and 45 on recording layer forming faces of the first substrates 31 and 35 have base part 511 and projecting parts 515 which are provided on about center of base part 511 and narrower than base part 511. Thus, the tracking error is reduced and the disk is made thin. Further, the sensitivity for write and S/N for read are high, and the production is easy, and the durability for use is good.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Background Technical Field of the Invention The present invention relates to an optical recording disk, particularly a heat mode optical recording disk.

Prior art optical recording disks have the characteristic that the recording disk does not deteriorate due to wear and tear because the medium and the writing or reading head are not in contact with each other, and for this reason, research and development of various optical recording media are being carried out.

Among such optical recording disks, heat mode optical recording disks are being actively developed because they do not require development in a dark room. This heat mode optical recording disk is an optical recording disk that uses recording light as heat. For example, a part of the medium is melted or removed using recording light such as a laser, and a part of the medium is melted or removed to create a pit. There is a bit forming type in which writing is performed by forming a small hole, information is recorded using this bit, and reading is performed by detecting this bit with a readout light.

Most of these bit-forming type disks, particularly those using a semiconductor laser as a light source that can make the device smaller, have a recording layer made of a material mainly composed of Te.

However, in recent years, it has been discovered that Te-based materials are harmful, and
Due to the need for higher sensitivity and lower manufacturing costs, an increasing number of proposals and reports are being made about media that use recording layers made of organic materials, mainly dyes, instead of Te-based ones. (Patent Application No. 19715, etc.)
.

In such a bit-forming type optical recording medium having a recording layer made of dye, etc., an air gap is provided on the recording layer in order to improve the efficiency of bit formation and improve sensitivity and S/N ratio. A so-called air sand inch structure is preferable.

In this case, the air sand inch structure uses a pair of optical recording parts having a recording layer on a transparent substrate made of resin, and integrates them so that the recording layers face each other with a predetermined gap in between. .

7jrJ6, FIG. 7, and FIG. 8 show conventional air sandwich structure optical recording disks.

In this case, the optical recording disc 1 has an optical recording portion 21 having a recording layer 71 on a first substrate 31 on the disc, and a second substrate 31 on the disc.
It has a substrate 6 and a spacer 9.

Tracking grooves 41 are formed on the recording layer forming surface of the first substrate 31 . This tracking groove 4
1 is one in which a partition wall is formed by a protrusion 51,
The first substrate 31 is connected to the second substrate 6 via the spacer 9.
When integrated with the air-sandwich structure, it forms an air sandwich structure.

However, in such a case, a gap exists between the protrusion 51 forming the groove 41 and the second substrate 6 on the recording layer 71, so it is necessary to make the disk thinner or to improve the strength of the substrate. Due to the need to make it thicker, Figures 9 and 1
As shown in FIG. 0, it is preferable to eliminate the gap between the protrusion 51 and the second substrate 6.

However, in such an optical recording disk, even if light is irradiated from the back side of the substrate, when writing or reading, the reflectance changes depending on the contact state of the protrusion 51 with the second substrate 6, so tracking control is not possible. There is a problem in that signal errors occur and tracking errors occur.

Such problems also occur in the case of double-sided recording in which the second substrate is used as a spacer substrate.

■Object of the Invention The object of the present invention is to integrate a pair of optical recording parts having a recording layer on a disk-shaped first substrate so that the recording layer is located inside, or In an optical recording disk that integrates a second substrate and a second substrate so that the recording layer is located on the inside, tracking errors are small, the thickness can be made thinner, or the substrate thickness can be made thicker, and the recording layer can be placed on the inside. The object of the present invention is to provide an optical recording disk that has high sensitivity and high S/N ratio during reading, is easy to manufacture, and has good durability during use.

■Disclosure of invention These objects are achieved by the invention described below.

That is, the present invention has a disk-shaped first substrate, a tracking groove is formed on this first substrate, a recording layer is provided on the surface where the groove is formed, and the recording layer is formed on the first substrate. In an optical recording disk that is integrated with a disk-shaped second substrate so as to be enclosed therein, a protrusion forming a partition wall of a tracking groove on a recording layer forming surface of the first substrate is formed between a base and a top surface of the base. This optical recording disk is characterized by having a convex portion that is smaller in width than the base portion provided approximately in the center of the disk.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

In the case of double-sided recording, the optical recording disc 1 of the present invention has a first
As shown in FIG. 2, a pair of optical recording portions 21.25 having a recording layer 71.7.5 and a first disc-shaped substrate 31.35 as a disc-shaped spacer are provided on a first disc-shaped substrate 31.35. It has two substrates 6.

In this case, the recording layer 71.75 is provided concentrically on the substrate 31.35.

The first substrate 31.35 to be used has a disk shape with a hole in the center into which the rotating shaft is inserted, and is substantially transparent (preferably has a transmittance of 8) to write light and read light.
0% or more) resin. This allows writing and reading from the back side of the substrate.

Note that the resin material used may be any of acrylic resin, polycarbonate resin, nylon, TPX, and the like.

Further, the disk diameter is approximately 90 to 300 mmφ.

Tracking grooves 41 and 45 are formed on the recording layer forming surface of such a substrate, as shown in FIGS. 3 and 4.

This tracking groove 41.45 is formed on the first substrate 31.
35 is formed by continuously providing protrusions 51 and 55 in a spiral or concentric manner in the circumferential direction.

As shown in FIG. 4, such a protrusion has a base 511 with a rectangular cross section. And this base 511
A convex portion 515 having a cross-sectional area smaller than the cross-sectional area of the base portion 511 and also having a rectangular cross-section is provided on the top.

This protrusion 515 is provided approximately at the center of the base 511, and the cutting spaces 81.8 are formed on both outer sides of the protrusion 515.
2 can prevent variations in the reflectance of write light, read light, tracking light, etc. irradiated from the back surface side of the first substrate 31.

The length of the base 511 of such a protrusion 51 in the track width direction is about 0.5 to 2-2, and the height is about 0.05 to 0.12. The width of the tracking groove 41 is about 0.5 to 2-2.

Further, the length of the convex portion 515 in the track width direction is 0.2 to 1
- degree, the height is about 0.05 to 0.1- degree, and the convex part 5
The length of the notch spaces 81 and 82 formed on both outer sides of the track width direction is about 0.1 to 1-. Note that the height of the protrusion 51, that is, the depth of the tracking groove 41, is usually about λ/8 n, particularly λ/7 n to λ.
/ 12 n (where n is the refractive index of the substrate).

Note that although the top surface of the convex portion 515 is normally flat as shown in the figure, it may be pointed if necessary.

Formation of such grooves on the substrate may be performed by a resin injection molding method, or may be performed by a 22 method.

In the case of the 2P method, a photopolymer is applied to a predetermined thickness on a flat substrate made of the above-mentioned various resins, and a stambar is pressed onto the photopolymer to cure it with ultraviolet rays to form grooves.

The recording layer located in the concave portion of the groove is used as a recording track portion, and writing light and reading light are irradiated from the back side of the substrate.

With this configuration, the writing sensitivity and the reading S/N ratio are improved, and the tracking control signal is also increased.

As mentioned above, by providing the notch space on both outer sides of the convex part of the protrusion, the writing light that was conventionally generated at the edge of the protrusion corresponding to the notch space,
It becomes possible to eliminate variations in the reflectance of readout light, tracking light, etc., and tracking control is significantly improved.

The second substrate 6 for a spacer that can be used in the present invention has a disk shape with a hole in the center into which the rotating shaft is inserted, and is usually made of the same resin as the first substrate 31, 35. .

In this case, the second substrate for the spacer may be opaque.

The optical recording portion 21.25 in which the recording layer 71.75 is provided on the first substrate 31.35 is integrated with the second substrate 6 for a spacer using a hot melt resin, an epoxy resin, a urethane resin, or a spacer. Diameter 0.1-0.5m that acts as
They may be integrated by adhesion using a UV curable resin containing beads of about m size.

In addition, if ultrasonic welding is used in combination, the convex portions of the protrusions can be effectively heated, resulting in good welding efficiency and workability.
Adhesive strength is high and void spacing can be controlled by stacking.

In this case, it is preferable that the cross-sectional shape of the convex portion 515 is somewhat sharp on the upper surface opposite to the base portion 511, rather than being rectangular as illustrated. Then, this sharp surface is melted and bonded by fusion.

Note that without using such a second substrate for a spacer,
It is also possible to use the substrate of one optical recording portion as a second substrate and bond the convex portions of the protrusions of the substrates of both optical recording portions to each other.

Alternatively, single-sided recording may be performed by using the spacer substrate described above as a back plate as the second substrate.

In this case, the second substrate may be transparent or opaque.

The recording layer of the present invention preferably consists of a dye alone or a dye composition.

The dye to be used may be appropriately determined from among those that effectively absorb the wavelengths of the writing light and reading light. In this case, these light sources are
Since it is preferable to use a semiconductor laser because the device can be made smaller, the dyes may be cyanine-based, phthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based,
Byrylium or thiapyrylium salts are preferred.

Further, when the dye composition is used as a recording layer, it can contain a self-oxidizing resin such as nitrocellulose, or a thermoplastic resin such as polystyrene or nylon. Further, in order to prevent oxidative deterioration of one dye, a clencher may be included. Furthermore, other additives may also be included.

In such a case, a mixture of an indolenine cyanine dye and a quencher such as bisphenyldithiol is particularly preferred.

It is also preferable to use these as an ionic bond between a dye cation and a quencher anion.

The recording layer can be made of ketone type, ester type, ether type,
A spinner coat or the like may be applied using an aromatic solvent, a halogenated alkyl alcohol solvent, or the like.

Such a recording layer 41.45 preferably has a thickness of 0.01 to 10 -.

In addition, when coating the recording layer, the viscosity of the coating solution is 0.5~
10cp, spinner rotation speed is 500~1. OOOr
Approximately pm.

Note that the thickness of the recording track portion in the recording layer is 0.2
P or less, more preferably 0.05 to 0.154.

At this time, writing sensitivity is improved. Further, due to multiple reflections in the recording layer, the reflectance becomes extremely high, and the read S/N ratio becomes extremely high. Then, the difference in reflectance based on the difference in thickness between the recording track portion and other areas increases, making tracking control easier.

A layer above the recording layer or an underlayer can also be provided on such an optical recording portion.

In addition, although the case of double-sided recording has been described above,
In the present invention, a single-sided recording medium may be used in which a recording layer is provided on only one substrate and this and a spacer substrate are integrated so that the recording layer is located on the inside. Also in this case,
The spacer substrate may be opaque.

(2) Specific Effects of the Invention The optical disc of the present invention irradiates writing light from the back side of the substrate while rotating. As a result, bits are preferably formed in a track shape in the recording track portion located in the groove recess.

The bits formed in this manner are detected by emitting readout light from the back side of the substrate while rotating and detecting the reflected light.

Further, in order to control tracking, normally, while writing and reading are being performed, the reflected light is divided and introduced into a pair of divided sensors. At this time,
When the beam spot begins to deviate from the recording track section, the primary light is biased towards one sensor due to the interference effect due to the phase difference due to the groove step, so the signals from both sensors are detected and a track error signal is detected.

Note that if the recording layer is formed from a dye composition containing a thermoplastic resin, the previously formed bits can be erased by light or heat and then written again.

In addition, the light source used for writing and reading is
Although various lasers can be used, it is particularly preferable to use a semiconductor laser.

■Specific Effects of the Invention According to the present invention, the recording layer formation surface of the substrate has a tracking groove, and the protrusions forming the partition walls of the groove are connected to the base;
Because it consists of a convex part located almost in the center of the base,
The reflectance of the tracking light irradiated from the back side of the substrate does not change at the edge of the protrusion, so tracking errors are extremely small, and the thickness of the substrate can be made thinner and thicker. An optical recording disk with extremely good sensitivity and read S/N ratio can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the optical recording disk of the present invention. FIG. 2 is a partially enlarged sectional view of FIG. 1. FIG. 3 is a sectional view showing one embodiment of a substrate used in the optical recording disk of the present invention. FIG. 4 is a partially enlarged sectional view of FIG. 3. FIG. 5 is a partially enlarged perspective view showing one embodiment of a substrate used in the optical recording disk of the present invention. 6 and 7 are a cross-sectional view and a partially enlarged cross-sectional view, respectively, showing one embodiment of a conventional optical recording disk. FIG. 8 is a partially enlarged perspective view showing one embodiment of a substrate used in a conventional optical recording disk. FIGS. 9 and 10 are a cross-sectional view and a partially enlarged cross-sectional view, respectively, showing one embodiment of a conventional optical recording disk. Explanation of symbols 1... Optical recording disk, 21.25... = Optical recording portion, 31.35... First substrate, 41.45... Groove, 51.55... - Projection, 511...Base, 6...Second substrate, 71.75...Recording layer, 81.82...Notch space, 9...Spacer patent application Representative TDC Co., Ltd. Patent attorney Yo Ishii -FIG, 4 FIG5 31 FIG, 8 FIG, 9 FIG, 10

Claims (1)

[Scope of Claims] A disk-shaped first substrate is provided, a tracking groove is formed on the first substrate, a recording layer is provided on the surface where the groove is formed, and the first substrate is provided with a recording layer. In an optical recording disk that is integrated with a disk-shaped second substrate so as to be enclosed therein, a protrusion forming a partition wall of a tracking groove on a recording layer forming surface of the first substrate is formed between a base portion and a base portion. What is claimed is: 1. An optical recording disk characterized in that it has a protrusion that is narrower than the base and is provided approximately in the center of the top.