JPS63160040A - Magneto-optical disk - Google Patents

Abstract

PURPOSE:To obtain a recovered clock by providing guide pits arranged at a pitch being an integral number of multiple or one over an integral number of the period of a clock frequency of a digital signal to be recorded to a disk base so as to read the guide pits. CONSTITUTION:The ruggedness string 32 for tracking is constituted by the guide pit 321 provided at the period being an integral number of multiple of one over an integral number of the clock frequency of a digital signal to be recorded. The clock is recovered and the data is read by tracking the guide pit 321 constituting the rugged string 32 of the information recording section of the magneto-optical disk. Since the period of the pit 32 is sufficiently shorter than the period of the response frequency of the tracking servo in the magneto- optical disk, the rugged string 32 with respect to the tracking is handled similarly as the continuous guide slot 31. Since the signal of the rugged string 32 appears at all times as to the rotating period, the servo characteristic with excellent response and stability is obtained by controlling the servo so as to make the period constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magneto-optical disks, and in particular to optical discs in which rotation speed standards, tracking standards, and clock standards for digital signals to be recorded are obtained from magneto-optical disks. It relates to magnetic disks.

[Conventional technology]

The information tracks of magneto-optical disks, which use laser light to record and reproduce information, have narrow spacing of about 1 μm to 3 μm, and in order to accurately trace the information tracks with laser light, they are arranged in a concentric or spiral shape called a pre-group. It is common to provide grooves in the disk base.

Since the number of information tracks on a magneto-optical disk reaches tens of thousands, in order to detect (search) the desired information track, some kind of address information must be recorded in advance on each information track or on each sector in which the information track is further divided. It is desirable to do so.

FIG. 5 (aJ, (b)) shows, for example, I B B E
These are a partially enlarged sectional view and a partially enlarged plan view showing a conventional recordable optical disk (magneto-optical disk) shown in Scheltram August 1979 issue, pages 26 to 33, in which 1 is a partially enlarged plan view. 2 is a recording film consisting of a magnetic film having perpendicular magnetic anisotropy and a dielectric protective film; 3 is an information recording section; A guide groove 31 having a length of λ/8 (λ is the wavelength of the recording/reproducing laser beam) is formed in advance. Reference numeral 4 indicates an address portion, in which address information bits 41 having a depth of λ/4 are formed in advance in the same manner as the guide groove 31 of the information recording portion 30.

Next, the recording/reproducing operation using the optical disc will be explained.

The light beam passes through the guide groove 31 of the information recording section 3 and the guide groove 31
Address information bit 41 of address section 4 which is an extension of
trace.

Note that the method used for this tracking is similar to the method used for tracking laser video discs or compact discs, and is well known, so a description thereof will be omitted. .

The address information bit 41 is formed so as to be self-lockable, and the light spot is located at the address section 4 of the optical disc.
Clock regeneration and address information reading are performed while the vehicle is running. The rotation speed of the optical disk is controlled by phase comparison between the rotation reference frequency and the reproduced clock (regenerated clock).
Writing of information (data) to be recorded is also performed in synchronization with the reproduction clock.

[Problem that the invention seeks to solve]

Conventional magneto-optical disks are constructed as described above, so when used as an optical disk, the number of blocks on one side is N%, and the number of information bits in the information recording section 3 per block is 1, Assuming that the number of address bits in the address section 4 is 2, the line information capacity M can be expressed as M = Nx (Kt -) - 2).

As mentioned above, address information bit 4 controls the rotation of the optical disk.
When synchronizing with the regenerated clock of No. 1, the response characteristics of the rotary servo are largely influenced by the frequency of appearance of the address section 4, and in order to make the response of the rotary servo quick and stable, the frequency of appearance of the address section 4 should be increased. It is necessary. In other words, it is nothing but increasing the number of blocks N, but
Since the line information capacity M is approximately constant as long as the disk size does not change, the sum of both bit numbers Kl and 2 (Kl+2) decreases in inverse proportion to the number N of blocks.

However, as the number of blocks N increases, the number of address bits representing each block increases in proportion to log N, so the number of information bits of 1 is much less, and the utilization efficiency of the optical disk (N x K17M) decreases. do. In other words, improving the rotational accuracy of an optical disk and improving the usage efficiency of the optical disk are contradictory elements, so the rotational accuracy.

There was a problem in that it was not possible to improve both utilization efficiency at the same time.

Conversely, when the number of blocks N is decreased, an error occurs between the actual rotation and the write clock to the information recording section 3 because the reproduced clock of the address section 4 is used, and there is no way to absorb this error. Since it is necessary to provide a margin for the number of information bits Kl, the number of bits that can actually be recorded is not small relative to the physical length of the information recording section 3.
There has been a problem in that the utilization efficiency of magneto-optical disks has deteriorated. When used as a magneto-optical disk, as mentioned above, the reproduced clock is obtained by reading the address information bit 41 provided only in the address section 4, so sufficient rotational accuracy cannot be obtained. First, there was a problem in that a separate clock generator had to be provided.

The present invention has been made to solve the above-mentioned problems, and aims to provide a magneto-optical disk whose rotation accuracy can be improved by a reproduction clock obtained by reading its own guide bit.

[Means for solving problems]

The magneto-optical disk according to the present invention is provided with guide bits arranged on a disk base at a period of l which is an integral multiple or an integral fraction of the period of the clock frequency of a digital signal to be recorded.

[For production]

In the magneto-optical disk according to the present invention, by reading the guide bits, it is possible to obtain a reproduction clock used as a rotational speed reference, a tracking reference, and a clock reference for a digital signal to be recorded.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1(a) and 1(b) are a partially enlarged sectional view and a partially enlarged plan view of an information recording section showing a magneto-optical disk according to an embodiment of the present invention (64), and the same parts as in FIG. 5 are designated by the same reference numerals. is attached. In FIG. 1, numeral 32 indicates a concavo-convex array for tracking, and this concave-convex array 32 is composed of guide bits 321 provided at a period that is an integral multiple or an integral fraction of the clock frequency of the digital signal to be recorded. has been done.

Next, the operation will be explained.

The magneto-optical disk of the present invention has a concavo-convex row 3 of an information recording section 3.
Clock recovery and data reading υ are performed by tracing the guide bits 321 forming part 2.

Normally, the upper limit of the tracking servo response frequency is several KH.
z, and in the magneto-optical disk of the present invention, the period τ of the guide bit 321 is a sufficient value for the period of the response frequency of the tracking servo. It can be treated as
Since the signal No. 2 always appears, servo characteristics with excellent responsiveness and stability can be obtained by controlling the period τ to be constant.

In addition, even if clock fluctuations that cannot be responded to by the rotation control system occur due to eccentricity of the temporary disk, the signal of the concavo-convex row 32 can be used as a clock reference for data reading and writing, thereby making it possible to determine the position where data should be written. Misalignment will no longer occur.

FIG. 2 is a schematic diagram showing the arrangement of the concavo-convex rows 32 of a magneto-optical disk used at a constant angular velocity.
(where rz>rl), it is shorter than the mechanical interval 12 of the guide bit 321 of the concavo-convex array 32, and has the following relationship: 1=rxθ (θ is constant).

FIG. 3 is a schematic diagram showing the arrangement of the concavo-convex rows 32 of a magneto-optical disk used at a constant linear velocity, and 11=12 regardless of the size of the radii rl and r2.

FIG. 4 is a partially enlarged sectional view and a partially enlarged plan view showing the vicinity of the boundary between the information recording section 3 and the address section 4 of a magneto-optical disk according to another embodiment of the present invention. The same symbols are attached.

In FIG. 4, 21 is a magnetized film having perpendicular anisotropy which constitutes the recording film 2, 22 is a dielectric protective film which constitutes the recording film 2, and 42 is an address information bit provided in the address section 4. This address information bit 42 is modulated and formed so as not to impair the periodicity of the period τ of the row of concave and convex portions 32 of the information recording section 3.

In this embodiment, an address information bit 42 for clock recovery is also provided in the address section 4, and the same effect as the embodiment shown in FIG. 1 can be obtained. Then, data reproduction is detected by rotating the polarization plane of the reflected light (or transmitted light), and clock reproduction from the concavo-convex row 32 is reproduced as a change in the intensity of the reflected light (or transmitted light), so the separation of both signals is possible. It can be easily done and both pips) 321. The degree of freedom for 42 is increased. Therefore, both pitches) 321°4
2 can be made to have the same depth, and recording on the master disc for creating the disc base 1 becomes easy.

In the above embodiment, an example of the configuration of the recording film 2 is shown in FIG. 4, but the configuration of the recording film 2 is not limited to the configuration shown in FIG. 4, and may have other configurations. .

〔Effect of the invention〕

As described above, according to the present invention, the guide bits are arranged on the disk base at a period that is an integral multiple or a fraction of the period of the clock frequency of the digital signal to be recorded. Since the reproduced clock can be obtained by reading K, rotation accuracy can be improved by using the reproduced clock.

It can also be applied to magneto-optical disks with constant angular velocity and constant linear velocity.

Still, since the depth of each bit provided in the information recording section and the address section can be made the same, there is an effect that recording on a master disk for producing a disk base becomes easy.

Furthermore, when used as an optical disc, there is an effect that usage efficiency can also be improved.

[Brief explanation of the drawing]

FIGS. 1(a) and 3(b) are a partially enlarged cross-sectional view and a partially enlarged plan view of an information recording section showing a magneto-optical disk according to an embodiment of the present invention, and FIGS. 2 and 3 are respectively shown at constant speed and A schematic diagram showing the arrangement of concavo-convex arrays on a magneto-optical disk with a constant angle of linear velocity, FIGS. 4(a) and 4(b) show the boundary between the information recording area and the address area of a magneto-optical disk according to another embodiment of the present invention. Partially enlarged @ side view and partially enlarged plan view showing the vicinity,
FIGS. 5(a) and 5(b) are a partially enlarged sectional view and a partially enlarged plan view showing the vicinity of the boundary between the information recording section and the address section of a conventional optical disc. In the figure, 1 is a disk base, 2 is a recording film, 3 is an information recording section, 32 is an uneven row, 321 is a guide bit, 4 is an address section, and 42 is an address information bit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 2 Figure 3

Claims (5)

[Claims] (1) In a magneto-optical disk in which a recording film is formed on a disk substrate, guides are arranged on the disk substrate at a period that is an integral multiple or a fraction of the period of the clock frequency of the digital signal to be recorded. A magneto-optical disk characterized by having a bit. (2) The magneto-optical disk according to claim 1, wherein the guide bits are arranged at equal angles with respect to the center of rotation. (3) The magneto-optical disk according to claim 1, wherein the guide bits are arranged at equal lengths in the circumferential direction. (4) Continuous guide bits are divided into a plurality of blocks by a certain number, and address information in an address section provided at the beginning of the plurality of blocks is modulated so as not to impair the periodicity of the guide bits. 4. A magneto-optical disk according to claim 1, wherein the magneto-optical disk is formed of address information bits. (5) The magneto-optical disk according to claim 4, wherein the depth of the address information bit is the same as the depth of the guide bit.