JPS6216259A - Information recording disk - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the noise and to make satisfactory the recording reproducing characteristic by using the part where the recording material between the information recording tracks is not provided, as the guide for the tracking. CONSTITUTION:On a recording disk 1, a recording track 3 and a groove-shaped part 4, in which the recording material is removed, are provided. Since a removed part 4 can be worked with a high accuracy, the difference in the reflecting light intensity of the high reflecting part and the non-reflecting part of the track 3 is detected and the correct tracking control is executed at the time of writing. The magnetic flux of a recording pit 3 forms the closed magnetic circuit through the removed part 4, and therefore, the diamagnetism is decreased, and the magnetic domain in the track is stabilized. Consequently, since the light is not reflected at the groove part, the occurrence of the noise is prevented and the recording reproducing characteristic can be made satisfactory.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an information recording disk, and more particularly to an information recording disk in which an information recording track portion and a track portion without recording material are formed on a disk-shaped substrate.

2. Description of the Related Art At present, research and development are being actively conducted in various fields on optical disk systems that use magneto-optical materials as high-density information recording media and are capable of erasing and rewriting records. In order to achieve high-density recording of recording signals, the area for recording a unit amount of information has become extremely small, and highly accurate position detection is required to record the signal at the desired recording position. .

For this purpose, spiral or concentric grooves are formed in advance on the disc-shaped substrate, and the recording position is detected by using the phase difference of the reflected light from this groove as tracking information, and the information recording signal is recorded at a predetermined position. This method is commonly used.

Conventionally, plastic materials have often been used as the material for this type of disc-shaped substrate. In addition, the grooves can be formed using injection molding method or 2P method (Photo Poly method).
marization) was commonly used. In other words, a stamper capable of forming grooves of a predetermined shape is prepared in advance, and a molten plastic material is injected into the stamper and solidified (gA bottom molding, or a resin that hardens with ultraviolet rays is filled, and the stamper is filled with a resin that hardens with ultraviolet rays, Grooves were formed directly on the disc-shaped substrate by applying ultraviolet rays from the direction and solidifying it (2P method), thereby creating a disc-shaped substrate with predetermined grooves.Then, on this disc-shaped substrate, a film such as vacuum evaporation was applied. A magneto-optical material was coated using this method, and an information recording disk was created using this coating.

Problems to be Solved by the Invention In general, acrylic and polycarbonate are often used as the above-mentioned plastic materials. However, although acrylic has relatively good optical properties, it has a problem in that the information recording disk is likely to warp due to its high water absorption. In order to prevent the negative effects of this warping, there are information recording disks that have a structure in which two acrylic disks are bonded together, but this structure has the problem of complicating the manufacturing process and increasing product costs. Ta. On the other hand, polycarbonate has low water absorption and is less prone to warping, but its optical properties, especially birefringence, are high, making it suitable for recording and recording good signals.
There was a problem that playback could not be performed. In addition, both acrylic and polycarbonate have a small surface height and are easily scratched. Furthermore, when the magneto-optical material is coated, the inside of the groove is also coated. Therefore, when reproducing the recorded signal recorded on the information recording disk, the laser beam irradiated to the information recording disk is reflected by the magneto-optical material coated in the groove, and this reflected light becomes noise in the reproduced signal. There was a problem that they were overlapped.

Here, considering the case where glass is used instead of plastic material as the material for the disk-shaped substrate, as is well known, glass has good optical properties, surface hardness, water absorption, and chemical stability. However, when creating a disk-shaped substrate made of glass, relatively simple groove forming methods such as injection molding or 2P method cannot be used, and it is generally not easy to form fine grooves on the glass surface. Rather, as mentioned above, although it has various characteristics suitable for information recording disks, it cannot be used as a disk-shaped substrate for information recording disks.

Therefore, an object of the present invention is to provide an information recording disk that solves the above problems by forming groove portions in which no recording material is disposed between the information recording tracks.

Means and Action for Solving the Problems In order to solve the above problems, the present invention provides a method of forming a portion where no recording material is disposed between the information recording tracks where the recording material is disposed and an information signal is recorded. However, this part is used as a tracking guide. With this configuration, it is not necessary to form a groove in the disk-shaped substrate, and tracking can be performed using the portion where the recording material is not provided as a reference.

Embodiment FIGS. 1 and 2 show an embodiment of the information recording disk according to the present invention. Note that FIG. 2 is an enlarged view of a cross-sectional view taken along line A-A in FIG. 1.

The information recording disk 1 shown in the figure has a configuration that allows erasing and rewriting of records, and includes a magneto-optical material arranged at predetermined positions on a disk-shaped substrate 2 made of glass to form information recording tracks 3. It is structured as follows.

The surface of the disc-shaped substrate 20 is a highly precise flat surface, and does not have any grooves or the like. In addition, since the disk-shaped substrate 2 is made of glass, it has good optical properties, surface hardness, water absorption, and chemical stability. ) This is a highly reliable substrate that does not cause birefringence of the laser beam incident on it, damage to the disk-shaped substrate 2, or warpage. The information recording track 3 (shown with a satin finish in FIG. 2) is, for example, T
It is made of a perpendicular magnetic recording material such as a b-Fe amorphous film, and a large number of concentric tracks are formed on a disk-shaped substrate 2 using various thin film forming methods and microfabrication methods described below. When recording an information signal, a recording bit corresponding to the information signal is formed on the information recording track 3 by the laser beam irradiated from the optical head and the perpendicular magnetic recording means, and when erasing, the recording bit is formed by the optical head. The information recording track 3 is irradiated with a laser beam, thereby erasing the recorded bits formed on the information recording track 3. Further, between each adjacent information recording track 3, a portion 4 from which recording material is removed (hereinafter, the portion from which recording material is removed will be referred to as a removed portion) is formed. This removal part 4
Since the surface of the disc-shaped substrate 2 is flat, it has a groove shape having a depth dimension corresponding to the coating thickness dimension of the recording material, but tracking information does not utilize this groove structure. Rather, it merely utilizes the difference between the surface reflection of the information recording track 3 and the non-reflection of the glass portion. Therefore, the depth of the groove, that is, the thickness of the information recording track 3, is not directly related to tracking.

This removing unit 4 first forms a film of recording material on the entire surface of the disk-shaped substrate 2 using, for example, a vacuum evaporation method, and then (1)
(2) A method in which the photoresist is left in a predetermined portion of the information recording track 3 by photolithography, and the recording material corresponding to the removed portion 4 is removed by etching. (3) irradiating the recording material at a position corresponding to the removal unit 4 with high-energy radiation G-A rays, electron beams, etc. to physically remove the recording material; It is formed. Therefore, the removal section 4 has a structure in which the surface of the disk-shaped substrate 2 made of glass is directly exposed.

Here, the function of the removing section 4 provided in the information recording disk 1 will be described below. Among the information recording disks on which recorded signals can be erased and rerecorded, the magneto-optical information recording disk 1 uses an optical head to irradiate a laser beam onto a predetermined position of the information recording track 3 on the information recording disk 1 during recording. Then, the temperature of the recording material is raised to near the Curie point, and a magnetic field is applied in the direction in which magnetization is desired. As a result, the magnetization at the laser beam irradiation position is reversed to the desired direction, and a recording bit is formed. The diameter of this recording bit is approximately 1 μm, which is a very small value, so that high-density recording can be achieved. Furthermore, reproduction processing is performed using the so-called Kerr effect, in which the plane of polarization of the laser beam reflected from the information recording track 3 is rotated by magnetization.

As mentioned above, the diameter of the recording bit is very small, so
It is necessary to control the tracking of the optical head with high precision. However, in the information recording circle 11 in which recording signals can be erased and rerecorded, there is no column of recording bits before writing, and tracking control cannot be performed. Therefore, it is necessary to provide a track groove for tracking on the information recording disk 1 in advance. As described above, conventionally, track grooves for tracking have been provided by forming irregularities on a disk-shaped substrate. However, in the present invention,
Tracking is performed by detecting the difference in reflected light intensity between a highly reflective part of the recording material and a non-reflective part where there is no recording material. Since the removed portion 4 is formed using a highly accurate processing method using photolithography technology or irradiation with radiation, electron beams, etc., its accuracy is extremely high and even if the track width is as small as about 1 μm, ,
Accurate tracking control can be performed using the removal unit 4 as a reference. In addition, since it is not necessary to form a track groove for tracking on the disc-shaped substrate 2, the disc-shaped substrate 2
Glass can be used as the material, and the highly reliable information recording disk 1 as described above can be realized. In addition, the manufacturing process can be simplified by eliminating the conventional "IJ Tt" process for the standber to form a tracking guide on the disk-shaped substrate 2, the injection molding process of plastic material into the standber, etc. , product costs can also be reduced.

In the information recording disk 1 having the above configuration, as a means for specifically controlling the tracking of the optical head, it is possible to use, for example, a well-known three-beam method. In other words, the main beam is narrowed and a pair of sub beams are provided,
Tracking control is performed by detecting the reflected light of this sub-beam. The information recording track 3 can reflect the irradiated laser light, and the removal section 4 has the disk-shaped substrate 2 made of glass directly exposed, so that the irradiated laser light is transmitted. Therefore, when the reflected light from each sub-beam is detected, tracking control of the optical head can be performed by displacing the optical head so that the intensity of both sub-beams becomes equal. Furthermore, as described above, since the removal section 4 has a structure in which the disk-shaped substrate 2 made of glass is directly exposed, the laser light irradiated to the removal section 4 is transmitted, and the amount of reflected light at the removal section 4 is reduced. Noise caused by the reflected light from the removal section 4 is not superimposed on the recording and reproduction signals, and information signals can be recorded and reproduced in good quality.

Also, considering the case where the removing section 4 is not provided, when perpendicular magnetic recording is performed on the information recording medium 5 as shown in FIG. When the bits are alternated, adjacent recording bits strengthen each other's magnetization to prevent demagnetization. However, depending on the type of recording M, as shown in FIG. 4, the direction of magnetization of each recorded bit may be the same. In this case, the above demagnetizing effect cannot be expected. However, as shown in FIG. 5, in the magnetic recording disk 1 having the removed portions 4, since the removed portions 4 in which no recording material is disposed on both sides of the information recording track 3 are formed, the magnetic flux of each recording pit 1 is Since a closed magnetic path is formed through this removal part 4 (indicated by a broken line arrow in the figure), the anti-vf1g is reduced, and the magnetic domain in the information recording track 3 made of perpendicular magnetic recording material can be stabilized. . Therefore, information signals can be recorded and reproduced in good condition.

Effects of the Invention As described above, according to the information recording disk of the present invention, a portion where no recording material is disposed is formed between the information recording tracks,
By using this part as a tracking guide, there is no need to provide a tracking track on the disc-shaped substrate, and therefore glass, which has good optical properties, surface hardness, water absorption, and chemical stability, is used as the material for the disc-shaped substrate. Since the disc-shaped substrate made of glass is directly exposed in the removed part where no recording material is placed, this part is not irradiated. The laser beam transmitted through the vortex is transmitted without being reflected, and the generation of noise in the recording/playback signal caused by the reflected light from the vortex, which is conventionally centered, is prevented and the recording/input characteristics are improved. Even if the magnetization direction of the recording bits recorded on the information recording track is all in the same direction, the magnetic flux of the recording bits forms a closed magnetic path through the removed part where no recording material is placed. , demagnetization is reduced and magnetic domains within the information recording track can be stabilized.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the information recording disk according to the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIGS. 3 and 4 show the removed portion. FIG. 5 is a diagram for explaining the magnetization direction of the recording bit and the stability of the magnetic domain in the information recording disk which is not provided with the information recording disk, and FIG. FIG. 3 is a diagram for explaining stability. 1... Information recording disk, 2... Disc-shaped substrate, 3...
Information recording track, 4...removal section.

Claims (1)

[Claims] An information recording disk characterized in that a portion where the recording material is not disposed is formed between the information recording tracks on which the recording material is disposed and an information signal is recorded, and this portion is used as a tracking guide.