JP2002092895A - Optical information recording and reproducing medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recording and reproducing information such that changes in the recording conditions for a recording head are small between the inner and outer circumferences on a disk during recording in the disk medium. SOLUTION: The varying range of the relative linear velocity between a head and a medium and changes in recording conditions during recording can be decreased by using the following disk medium and by the following method. In the disk medium used, the tracks on the recording medium are divided into a plurality of regions according to the radial position of the tracks in such a manner that the radial width which is the length in the radial direction of a region is smaller in a relatively inner region than in a relatively outer region. The recording medium is rotated at such a speed of revolution that the angular velocity varies by the regions to which the recording tracks belong and is constant in each region and that the angular velocity decreases with the regions to which the recording tracks belong in the radial positions nearer to the outer circumference of the medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing method for recording / reproducing information on / from a recording medium on a disk such as an optical disk and a magnetic disk.

[0002]

2. Description of the Related Art In recent years, with the development of semiconductor technology, the capability of digital signal processing has been dramatically improved, and electronic equipment such as computers can process a large amount of information data at high speed. Accordingly, a storage medium for recording and reproducing information is required to have a larger capacity and to handle information at higher speed. Above all, media on disks such as optical disks and magnetic hard disks (hereinafter referred to as disks)
Attention has been focused on a method of recording and reproducing information using a recording and reproducing head.

An example of the above-described conventional information recording / reproducing method for an optical disk will be described with reference to the drawings. FIG. 6 is a schematic diagram showing a configuration of a general optical disk recording / reproducing apparatus.

[0004] The basic structure of an optical disk is such that a recording thin film layer whose state changes by irradiation with laser spot light is provided on a disk-shaped base material having a flat surface. The following methods are used for recording and reproducing signals. That is, the disk 1 is rotated by a rotating means 4 such as a motor at a predetermined number of rotations a and relatively moved with respect to the optical head 2, and the laser beam 6 emitted from the optical head is converged and irradiated onto the recording thin film surface of the medium. I do. At this time, a known focusing is performed so that the laser beam 6 converges on the recording thin film surface.
Control technology is used. The recording thin film absorbs the laser beam 6 and rises in temperature. When the output of the laser beam 6 is increased above a certain threshold value according to the information to be recorded, the state of the recording thin film partially changes and information is recorded. This threshold value is an amount that depends on the characteristics of the recording thin film itself, the thermal characteristics of the substrate, the relative speed (linear velocity) v of the medium to the optical head, and the like. Further, the recording state changes depending on recording conditions such as the output of the laser beam having the size of the laser beam or the pulse width.

Normally, recording and reproduction are generally performed by changing the output intensity using the same light beam emitted from the same optical head 2, but recording and reproduction are performed separately by different optical heads, It is also possible to carry out with a recording head and a reproducing head. In the following, the recording head and the reproducing head will be described according to the operation including the case where the same head is used.

The recorded information irradiates the recording portion with a laser beam spot having an output sufficiently lower than the threshold value from the reproducing head, and the optical characteristics such as the transmitted light intensity, the reflected light intensity or the polarization direction thereof are changed. And the difference between the unrecorded portion and the reproduced portion. At this time, a known tracking control is usually performed so that the laser beam accurately follows a series of states recorded and changed, that is, a recording track. There is also a technique in which a tracking guide is provided in advance by means such as forming an uneven groove-shaped track on a base material, and recording / reproduction is performed while performing tracking control using the guide.

At the time of recording, the recording is performed on a concentric circle on the disk surface by fixing the recording head on the transfer mechanism 5. Further, by recording while moving the recording head on the transfer mechanism 5 in the radial direction of the disk, recording is performed on a spiral having a predetermined feed pitch (track pitch). In any case, the track 3 to be recorded is formed substantially on the circumference. When a guide for tracking is provided in advance, it is generally formed on a substantially circumference.

Conventionally, when performing recording and reproduction on such a disk, recording and reproduction have been performed while always rotating the disk at a constant rotational speed. FIG. 4 is a graph showing the relationship between the recording position, the rotation speed, and the linear velocity in the conventional information recording / reproducing method. Such a method is called a constant rotation angle (C
AV: Constant angular velocity (AV) method.

In the CAV method, as shown in FIG. 4, the relative velocity (linear velocity) between the recording head and the track on the disk is proportional to the radius and is smaller toward the inner circumference in accordance with the radius of the track to be recorded.

FIG. 4 shows that the rotational speed a of a disk having a diameter of 130 mm is 1
An example is shown in which recording and reproduction are performed at an area with a radius r of 30 mm to 60 mm by rotating at 800 rpm. In this case, the linear velocity v changes from the innermost circumference of 5.65 m / s to the outermost circumference of 11.30 m / s.

In addition, as shown in FIG. 5, there is also known a method of changing the number of revolutions on the inner and outer circumferences so that the linear velocity becomes constant, that is, a constant linear velocity (CLV) method. FIG. 5 shows an example in which a disk having a diameter of 130 mm is rotated at a constant linear speed of 5.65 m / s and recording / reproducing is performed in an area having a radius r = 30 mm to 60 mm. In this case, the rotation speed a continuously changes from the innermost circumference of 1800 rpm to the outermost circumference of 900 rpm.

In both the CAV system and the CLV system, the relationship between the radius and the number of revolutions or the linear velocity during recording and during reproduction is the same.

[0013]

However, in the above-described CAV method, the linear recording speed is different between the inner and outer circumferences of the disk, so that the optimum recording conditions are different. Had to be changed. In the CLV method, since the linear velocity is constant, it is not necessary to change the recording condition of the recording head. However, it is necessary to change the number of rotations of the disk in accordance with the position of the inner and outer circumferences. There is a problem that the search time becomes longer due to the limitation of the time (pull-in time) required for the rotation speed to change to a predetermined value corresponding to the radial position at the time of search (access).

If the linear velocity differs, the threshold of the laser beam output (power) generally required for recording changes. When the linear velocity is high, relatively large power is required. If the power is too large, the recording medium may be damaged. It is necessary to change the recording power to an optimum value according to the linear velocity.

In the case of a phase change type optical recording medium in which recording is performed by changing the crystal state of the recording thin film, the recording thin film is melted by irradiating a laser beam having a relatively strong recording power to rapidly cool the recording thin film. The thin film is made amorphous to record information and irradiated with a relatively weak erasing power to crystallize the thin film in a solid phase to erase the information. Since crystallization is a rearrangement of atoms, it takes a predetermined time.However, when such a phase-change type recording medium has a high linear velocity, the time required for heating by laser light irradiation becomes relatively short, and the crystallization takes place. Insufficiency in erasing results in a decrease in erasing performance. Also, when the linear velocity is low, even if the thin film is melted by irradiating the recording power, rapid cooling conditions cannot be obtained and the film is gradually cooled and tends to crystallize in the solidification process, so that an amorphous recording mark is hardly formed. As described above, the recording state of the optical disk largely depends on the relative linear velocity between the optical head and the recording track.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method for controlling the rotation of a disk in which the recording conditions of the recording head change little at the inner and outer peripheral positions on the disk during recording, and the search time for an arbitrary recording track is short during reproduction. It is an object of the present invention to provide an information recording / reproducing method using a method.

[0017]

In order to solve the above-mentioned problems, an information recording / reproducing method according to the present invention uses a disk-shaped recording medium while rotating a disk-shaped recording medium on a track provided substantially on a circumference at a specific radial position. As a method of sequentially recording information by a recording head and sequentially reproducing the information recorded on the track by a reproducing head while rotating the recording medium, a track on the recording medium is divided into a plurality of areas by its radial position. However, the divided region uses a disk medium characterized in that the radial width, which is the radial distance of the relatively inner region, is smaller than the radial width of the relatively outer region, and the angular velocity is to be recorded during recording. The recording medium is rotated at a rotational speed such that the angular velocity is constant in the area, and the angular velocity is constant in all areas during reproduction. Rotating the recording medium at Do rpm,
It is provided with such a configuration.

[0018]

According to the present invention, since the variation range of the relative linear velocity between the recording head and the disk during recording is small due to the above configuration,
A change in the recording condition of the recording head can be small, and it is sufficient to rotate the recording head at a constant rotation speed during reproduction, and the time for searching for an arbitrary recording track can be shortened.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An information recording / reproducing method according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the relationship between the radius, the number of revolutions, and the linear velocity in the information recording / reproducing method according to the embodiment of the present invention. FIG. 1 shows an example in which recording / reproducing is performed on a region having a radius r of 30 mm to 60 mm of a disk having a diameter of 130 mm. The recording area of the disc is divided into three equal areas in the radial direction with radii r = 30 to 40 mm, 40 to 50 mm, and 50 to 60 mm. At the time of recording, the recording medium is rotated at a rotation speed such that the angular velocity decreases as the radial position of the area to which the track belongs on the recording medium becomes closer to the outer periphery.

As shown in FIG. 1, the rotation speed is 1800 rpm in the region of radius r = 30 to 40 mm, 1350 rpm in the region of r = 40 to 50 mm, and 1080 rpm in the region of r = 50 to 60 mm. In this case, the relative linear velocity between the track to be recorded and the recording head is 5.65 to less in the region of radius r = 30 to 40 mm.
7.53m / s, 5.65-7.07 in the area of r = 40-50mm, and r
In the range of 50 to 60 mm, it falls within the range of 5.65 to 6.78 m / s.
Therefore, when such rotation control is performed, the range of the relative linear velocity between the track to be recorded and the recording head is substantially the same for each area to which the track belongs, and the range is smaller than that of the conventional example. In this example, as described above, in the conventional example, the fluctuation range of the linear velocity changes twice from 5.65 to 11.30 m / s, but in this example, it changes only 1.33 times. If the number of divisions of the area is further increased, the fluctuation range of the linear velocity is further reduced. For example, if the same radius r = 30 mm to 60 mm region is equally divided into 10 in the radial direction, the linear velocity variation range is 1.1
Double it.

Furthermore, the area is divided unevenly in the radial direction.
If the number of divisions is the same, the above linear velocity fluctuation range should be reduced.
Can be. It is the minimum linear velocity and maximum linear velocity within each area
This is the case where the division is performed so that the speeds match each other.
Let the radius of the outermost circumference of the recording area be r _oAnd the innermost radius is r_i,
Assuming that the number of divisions is n, radius r = r_i(R_o/ R_i)^{(
x / n)} (Where x is an integer of 1 ≦ x <n), and the rotation speed a = 2πr in each region._ia_i(R_o/ R_i)
^{(Y / n)} (However, a_iIs the rotational speed in the innermost peripheral region, and y is 0 ≦ y <n
The disk speed can be changed by the integer
The change in degree is (r_o/ R_i)^{(1 / n)}Double. With the above
Similarly, when dividing the area of radius r = 30mm to 60mm into 3
The recording area has a radius r = 30 to 37.80 mm, 37.80 to 47.62 mm, and
And 47.62-60 mm, the radial width which is the radial distance
Is divided into 7.8mm, 9.82mm, and 12.38mm from the inner circumference, respectively.
The linear velocity fluctuation is 1.26 times in each area. Likewise
If you divide it into ten, it will be 1.07 times, and each will be equally divided
In this case, the linear velocity fluctuation becomes smaller than that in the case.

As described above, in addition to the fact that the fluctuation range of the linear velocity in each area is small, if the range from the minimum linear velocity to the maximum linear velocity is the same or substantially the same in each area,
There is also an effect that the structure and accuracy of the rotating means 4 such as a motor or the control means for controlling the rotating means 4 are simplified and the cost of the apparatus is reduced.

In an optical disk, a signal is reproduced by detecting reflected light or transmitted light of the irradiated laser light and reproducing the recorded information from the change. Therefore, even if the linear velocity changes, the output of the laser light at the time of reproduction, etc. There is no need to change the conditions. Therefore, when reproducing the recorded signal, as shown in FIG. 1, the reproduction can be performed by rotating at the same rotation speed in all the regions. FIG. 1 shows a case in which reproduction is performed at the rotational speed when recording is performed in the innermost area, but if it is constant in each area, it may be rotated at another rotational speed. When the optical head is moved by the transfer mechanism 5 to search for a track at an arbitrary radius on the disk by always rotating the disk at the same rotation speed in this manner, the rotation speed of the disk is not changed. High-speed search can be performed without waiting time required for rotation control.

On the other hand, if the rotational speed differs between recording and reproduction as described above and the relative linear velocity between the optical head and the track differs, the reproduced signal is compressed or expanded in the time axis direction with respect to the recorded signal. Will be played. In other words, the timing clock frequency of the reproduction signal differs from the timing clock of the recording signal. Therefore, the recording / reproducing apparatus needs to have means for restoring the compression / expansion of such a signal in the time axis direction. It is well known that such means are possible by having a plurality of master timing clocks on the device side.

In order to avoid such a change in the time axis direction of the signal during recording / reproducing, each area is also rotated at the same rotational speed as at the time of different recording at the time of reproducing, and the optical head at the time of recording and reproducing at the same track. It is also possible for the relative linear velocities of the tracks to be the same. FIG. 2 shows the relationship between the radial position of the track to be recorded / reproduced on the disk, the rotational speed of the disk, and the relative linear velocity between the head and the track in this case.
In this case, there is an effect that the number of rotations is uniquely determined by the position on the disk of the track irradiated with the laser of the optical head regardless of recording and reproduction.

In addition to the above-mentioned several methods of dividing the recording area on the disk, the recording medium is rotated at a rotational speed such that the relative linear velocity between the track to be recorded and the reproducing head is always constant during recording. It is also possible to rotate the recording medium at a rotational speed that makes the angular velocity constant during reproduction. FIG. 3 shows the relationship between the radial position of the track to be recorded / reproduced on the disk, the rotational speed of the disk, and the relative linear velocity between the head and the track in this case. That is, the rotation control of the CLV method during recording and the rotation control of the CAV method during reproduction may be performed. In this case, since the relative linear velocities of the optical head and the track are always the same during recording, there is no need to change the recording conditions. In addition, at the time of reproduction, since rotation is performed at a constant rotation speed, access to an arbitrary track can be performed at high speed without waiting for rotation control.

[0028]

As described above, according to the present invention, a track on a disk medium is divided into a plurality of areas by its radial position, and the divided area has a radial width which is a radial distance of a relatively inner area. Using a disk medium smaller than the radial width of the relatively outer area, the recording medium is rotated at a rotational speed that is different for each area to which the track to be recorded belongs during recording, and is constant within the area, During playback, it consists of rotating the recording medium at a rotational speed that keeps the angular velocity constant in all areas.During recording, changes in the recording conditions of the recording head at the inner and outer peripheral positions on the disc are small. Sometimes, it is possible to provide a method of recording and reproducing information on a disk in which the search time for an arbitrary recording track is short.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between a radial position of a track to be recorded / reproduced on a disk, a rotational speed of the disk, and a relative linear velocity between a head and a track in the first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a radial position of a track to be recorded / reproduced on a disk, a rotational speed of the disk, and a relative linear velocity between a head and a track in the second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between a radial position of a track to be recorded / reproduced on a disk, a rotational speed of the disk, and a relative linear velocity between a head and a track in a third embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a radial position of a track to be recorded / reproduced on a disk, a rotational speed of the disk, and a relative linear velocity between a head and a track in the conventional method.

FIG. 5 is a characteristic diagram showing a relationship between a radial position of a track to be recorded / reproduced on a disk, a rotational speed of the disk, and a relative linear velocity between a head and a track according to another conventional method.

FIG. 6 is a schematic diagram illustrating a configuration of a recording / reproducing apparatus using an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 disc 2 optical head 3 track 4 rotating means 5 transfer mechanism 6 laser beam

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kenji Ohno 1006, Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Noboru Yamada 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. 5D044 BC02 CC06 DE03 DE77 5D090 AA01 CC14 DD01 DD05 GG02 GG11

Claims (5)

[Claims] 1. A recording thin film provided on a disk-shaped base material is irradiated with a laser beam to generate heat, thereby increasing the temperature and partially changing the state of the recording thin film to record information. An optical information recording / reproducing medium for detecting a change in optical characteristics due to a difference between partial changes in the state of the recording thin film and reproducing recorded information, wherein a substantially circular shape is formed at a predetermined radial position on the recording medium. A circumferential track is formed, divided into a plurality of areas according to the radial position of the track, and a radial width that is a radial distance of a relatively inner area is smaller than a radial width of a relatively outer area. An optical information recording / reproducing medium characterized by the above-mentioned. 2. A method for irradiating a recording thin film provided on a disk-shaped base material with laser light to generate heat and raise the temperature to partially change the state of the recording thin film, thereby recording information, and irradiating the laser light. An optical information recording / reproducing medium for detecting a change in optical characteristics due to a difference between partial changes in the state of the recording thin film and reproducing recorded information, wherein a substantially circular shape is formed at a predetermined radial position on the recording medium. An optical information recording / reproducing medium, wherein a circumferential track is formed, the track is divided into a plurality of areas according to a radial position of the track, and a radial width of an outermost area is larger than a radial width of another area. 3. A recording thin film provided on a disk-shaped base material is irradiated with laser light to generate heat and raise the temperature to partially change the state of the recording thin film to record information. An optical information recording / reproducing medium for detecting a change in optical characteristics due to a difference between partial changes in the state of the recording thin film and reproducing recorded information, wherein a substantially circular shape is formed at a predetermined radial position on the recording medium. An optical information recording / reproducing medium, wherein a circumferential track is formed, the track is divided into a plurality of areas according to a radial position of the track, and a radial width of an innermost area is smaller than a radial width of another area. 4. The method according to claim 1, wherein a radius of the outermost region is larger than a radius of the other region, and a radius of the innermost region is smaller than the radius of the other region. 4. The optical information recording / reproducing medium according to any one of 2 and 3. 5. When the radius of the outermost periphery of a region is r _o , the radius of the innermost periphery is r _i , and the total number of regions is n, the radius r = r _i (r _o /
2. The optical information recording / reproducing medium according to claim 1, wherein the area is divided into a plurality of areas by r _i ) ^{(x / n)} (where 1 ≦ x <n).