JPS6342055A - Magneto-optical recording method - Google Patents

Abstract

PURPOSE:To perform what is called overwrite by making the recording magnetic field opposite between the N-th recording and the (N+1)th recording. CONSTITUTION:Upward magnetized bits are indicated by oblique lines, and downward magnetized bits are indicated with white frames. Two bits are used to record one signal '1' or '0'. In case of the N-th recording, the recording magnetic field is preliminarily applied upward and only pertinent bits are magnetized downward in accordance with signals '1-1-0-0' to be recorded. Then, in case of the (N+1)th recording, the recording field is preliminarily applied downward and only pertinent bits are magnetized downward in accordance with signals '1-0-1-0' to be recorded. Thus, it is unnecessary to erase recorded signals before signals are recorded, and only 1/32 rotation of the disc is required for recording of signals on one sector, and therefore, the erasing and recording time is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This article 9.11 relates to a magneto-optical recording method that enables override n in a magneto-optical disk device.

[Prior Art] Magneto-optical recording records information by utilizing the interaction between local heating of a recording medium by a focused laser beam and a magnetic field existing in the area.

FIGS. 7(a) and 8(b) and FIG. 8 are diagrams schematically showing the principles of recording, erasing, and reproducing magneto-optical recording, respectively.

During recording, the magnetic film l, which is easily magnetized in the direction perpendicular to the film surface of the magneto-optical disk, is magnetized in advance in the same direction, and local heating is performed using a laser beam 2 in a recording magnetic field H7 having a coercive force Hc or less of the film. The magnetization is then raised to one Curie temperature to cause the magnetization to disappear, and when the magnetization is recovered during the cooling process, it is reversed by the recording magnetic field H (Fig. 7 (a)). For erasing, as with recording, heating with the laser beam 2 and application of the magnetic field are performed. However, the direction in which the erasing magnetic field H2 is applied is opposite to the direction of the recording magnetic field H7 (FIG. 7(b)).

For reproduction, the direction of recorded magnetization is read out using a continuous laser beam that is weaker than for recording and erasing, and in this case, the magnetic Kerr effect, which is the interaction between light and magnetism, is used.

Light is also a type of radio wave, with electric and magnetic fields vibrating in a plane perpendicular to its direction of propagation. The electric field (5a field) of the laser beam oscillates in one direction. When the light is irradiated onto the surface of the recording medium l and reflected, the vibration directions rotate in opposite directions depending on the direction of magnetization of the medium.

This phenomenon is called the magnetic Kerr effect, and as shown in Figure 8 (a), if each rotates by ±θ, the angle between them will be 2θ. For example, if the passing axis 5 is magnetized downward and perpendicular to the vibration direction of the reflected light 3, the light will not pass through the analyzer 10 (see Fig. 8).
b)), and the light 4 reflected by the magnetization in the L direction is sin 2θ
, and the amount of light is detected by the photodetecting element 11 (Fig. 8 (C)). Therefore, the rotation of the light vibration plane due to the magnetization direction of the recording surface is converted into the corresponding intensity of light. , it is possible to detect the recorded information.

FIG. 9 is a diagram showing an example of a magneto-optical disk device employing the above-mentioned magneto-optical recording method, in which (a) is a schematic side view and (b) is a plan view of the disk. , 21 is an optical head that emits a laser beam and reads reflected light from the magneto-optical disk 22, that is, erases, records, and reproduces information; 23 is a coil for forming a recording magnetic field; 24 is an optical head that reads the reflected light from the magneto-optical disk 22; It is a motor that rotates. The optical system 21 and the coil 23 are moved in the radial direction of the disk 22 by a drive device (not shown), and erase, record, and reproduce all tracks on the disk 22.

Usually, the track 25 of the disk 21h is spiral or concentric (FIG. 9(b) shows a concentric circle), and one rotation of the disk 22 is equally divided into several sectors. Now, if we assume that the division is divided into 32, when information is to be recorded in a certain l sector, for example, sector S, the disk 22 must be operated by an erasing laser to first erase the signal already recorded in sector S1. It rotates 1/32 while receiving light in the sector portion. At this time, Fig. 7(b)
As shown in the figure, the downward 5a field H is applied, so
The signal is erased by magnetizing everything downward. Since the disk 22 is rotated at high speed in one direction by the motor 24, it cannot be reversed, so it is then rotated 31/:12 in the same direction until the laser beam hits the first part of the sector again. From here, while the disk 22 rotates 1/32, a recording magnetic field Hll is applied upward as shown in FIG. By creating a magnetized part, a digital signal (1-
〇signal).

[Problems to be Solved by the Invention] However, in the above recording method, the disk 22 is
: To record the area for 32 revolutions, the disc 22 is
This means that you will have to complete 3/32 rotations.

In other words, it took 33 times as long to erase and record one sector's worth of signals, which is much longer than the actual recording time of one sector, and the recording speed was 8 times slower. be.

[Means for Solving the Problems] The purpose of the unreleased IJ1 is to provide a magneto-optical recording method that solves the disadvantage of the long information recording time of the conventional example described above and makes so-called override an iT sushi. The above purpose is to use a magneto-optical recording method that records information by irradiating light onto a magneto-optical recording medium.
This is achieved by a magneto-optical recording method characterized by reversing the direction of the recording magnetic field between (N=1, 2.3, . . . ) and (N+ 1 ) second recording.

In the present invention, when recording a binary signal on a magneto-optical recording medium having the first and second magnetization directions,
1st. By recording information using two types of magnetization patterns corresponding to the binary signals in each direction of the second Q magnetic field, various advantages can be obtained.

[Examples] Hereinafter, the magneto-optical recording method according to the present invention will be described in detail based on specific examples.

FIG. 1 is a diagram showing a first embodiment of the present invention, and in the following description, bits magnetized upward as shown in FIG. 1(a) are indicated by diagonal lines, and FIG. 7(a) (equivalent to ), and the downwardly magnetized bit is indicated by a white frame (Fig. 7(b)).
In addition, in this embodiment, when recording (1-0 numbers) on the disk, 2 bits are used to record one signal "1" or "0". On the other hand, in the conventional example, for example, if the upward magnetization bit is an "l" signal, the downward magnetization bit is a "0" signal.

In this embodiment, as shown in FIG. 1(b), when the recording magnetic field is magnetized in the magnetic field, a "0" signal is represented by two upwardly magnetized bits, and a '1' signal is represented by one upwardly magnetized bit, followed by a downwardly magnetized bit. In addition, when downward magnetization is performed, a “0” signal is expressed by two downward magnetized bits, and an “L” signal is expressed by one downward magnetized bit followed by one downward magnetized bit. represent.

The first [j6(c) is an explanatory diagram when the recording method of this embodiment is repeated a plurality of times. Now, when performing the Nth recording, the recording magnetic field is applied upward as in FIG. 7(a), and the upward magnetized bit portion is Since the laser beam is irradiated only on the part to be magnetized, only the corresponding part becomes the L-direction magnetized bit part. When using the disk for the first time, for example, when shipping the disk from the factory, all bits should be magnetized downward.
When performing the next (N+1)th recording, the recording magnetic field is
As with +2(b), apply the laser beam downward, and according to the signal "l-0-1-0" to be recorded, the laser beam is irradiated only on the part that should be the downward magnetized bit as shown in the figure, so only the corresponding part is irradiated. This becomes the downward magnetized bit part. There is no problem because the part that should become the upward magnetized bit can be used as is during the Nth recording.0th order (N+2)
When recording for the th time, the recording magnetic field is applied in the same direction as the Nth recording, and the signal to be recorded is “0-1-1-
As shown in the figure, the laser beam is irradiated only on the part that should be magnetized in the t-direction as shown in the figure, so that only that part becomes the upwardly magnetized bit part.The part that should be the downwardly magnetized bit part is (
N+ 11 times [There is no problem because the part that becomes the downward magnetized bit during one recording can be used as is.Reverse the direction of the recording magnetic field every time the number of recordings exceeds 0, and write the signal (see Figure 1) There is no limit to the number of items (not just four as shown in C)).

In the above description, in order to irradiate a laser beam only to a portion to be an upwardly or downwardly magnetized bit, it is necessary to know the position in advance, and the -F step will be described later. However, in this embodiment, if the irradiation is not limited to only the corresponding magnetized bits during the three-switching of recording, S switching can be performed without knowing the recorded recording pattern. , as shown in Figure 2,
If information is recorded with an upward magnetic field, the recording magnetic field is r
If the data to be recorded next is "0", the laser is irradiated for 2 bits, and if it is "t", the laser is irradiated for the last 1 of the 2 bits.
By irradiating a bit with a laser, even if the previous recorded data is "0" or "l", it can be replaced (see Figure 2 (a) and (b)). Recording is performed using a downward magnetic field. Similarly, for the recorded information, the magnetic field is directed upward, and if the next data to be recorded is 'O', the laser is irradiated for 2 bits, =
If it is 1", rewriting can be performed by irradiating the previous 1 bit of the 2 bits with a laser (Figure 2 (C)
, (d) See! ! I1. ).

Here, if we consider the recording speed of the present invention by taking as an example the case where a signal is recorded in one sector out of 32 divisions corresponding to one revolution of the disk, as in the conventional example, in the present invention, the recording speed is recorded before recording the signal. Since it is not necessary to erase the signal, the disk only needs to rotate 1/32 times to record the signal in 1 sector, and the erasing and recording time can be significantly shortened compared to the conventional example.

In the present invention, when a general recording pattern not limited to this embodiment is used, the recording magnetic field (in other words, "O", "1" of already recorded information) is used for recording a signal.
The magneto-optical disk device must determine whether the direction of magnetization on the track (which is used as a reference for determining the direction of magnetization) is upward or downward.The method for this determination is as follows:
- For example, a method may be considered in which information about the direction of the recording magnetic field at the time of previous recording is recorded together with management information for managing a certain area of the disk, such as a sector. Alternatively, it is also possible to provide a management sector for each track in which information about the magnetic field direction of the recording sector on the track is recorded.For example, when recording information for each sector, the management area is read and the information is The m* direction of the previous recording of the sector is known, the magnetic field direction of the current recording is written, and the information of the sector is rewritten. Therefore, in this case, the direction of the recording magnetic field will vary from sector to sector. Note that in handling the management information, it is possible to shorten the time by using not only the above-mentioned method but also various methods.

The embodiments of the present invention described above describe magnetization patterns recorded on magneto-optical disk balls, and the recording method of the present invention can be used after data is modulated by a conventional modulation method. By doing this, the "O'" signal will not be continuous, and bit synchronization or clock synchronization will be ensured. Since it is within 7, bit synchronization or clock synchronization can be achieved.In the case of other modulation methods, it is sufficient as long as the minimum inversion interval is kept regular.

Furthermore, even when directly recording data using the recording method described in Incomplete 11 without using various modulation methods, bit synchronization can be achieved by providing at least one magnetization reversal in the magnetization patterns corresponding to "0" and "1". An example of a recording pattern in this case is shown in FIG.

In addition, in order to achieve bit synchronization, as shown in Figure 4, when recording patterns compatible with data video are continuously recorded, a recording pattern 30 (periodic pattern) having magnetization reversal for bit synchronization or clock synchronization is inserted. I can think of something to do. By inserting such a synchronization pattern and making the synchronization pattern a special pattern, data can be synchronized. Of course, as shown in FIG. 5, data synchronization can also be achieved by separately providing a special pattern 31 for data synchronization.

When the recording pattern shown in Figure 1 is used, is it possible to perform the next recording without knowing the recording pattern of the previous recording? ” is magnetized in the L direction of 3 bits, “l” is 2 out of 3 pits
There are 3 patterns in which the bit is magnetized upward, and 3 hits of "0" during downward magnetization recording, 3 hits of downward magnetization, '1
'' is three patterns in which 2 out of 3 bits are magnetized downward, and when recording "l" with a downward magnetic field, it is necessary to judge which pattern is the previous recording pattern of upward magnetization. Therefore, when adopting a recording pattern as shown in Figure 7, a reading beam is provided in advance of the recording beam in order to read the previous data, and after reading the data of the track record, the reading beam is Then, a laser beam is irradiated to change the pattern.

Also, the first ['A
Even if a pattern of (e.g.), unnecessary laser irradiation can be avoided.This will have the effect of extending the lifespan of the laser, and will also prevent pattern deformation since it will not be magnetized in the same direction multiple times. Kotoka C Kiruru.

Furthermore, by arranging the reading beam behind the recording beam, it is also possible to verify the recorded data at "rtm".

[Effects of the Invention] As explained below, according to the magneto-optical recording method according to the present invention, by reversing the direction of the recording magnetic field at the time of Nth recording and at the time of (N+1)40th recording, so-called By making override unnecessary, signal erasure recording time can be significantly shortened.

[Brief explanation of the drawing]

Figure 1 (a), (b), (C), Figure 2 (a), (b)
, (c), and (d) are explanatory diagrams for explaining the first embodiment of the magneto-optical recording method of the present invention, respectively, and FIG. 3 is an explanatory diagram of an embodiment having at least one magnetization reversal in the pattern. , FIGS. 4 and 5 UA are explanatory diagrams of an embodiment in which bit synchronization or clock cycles are provided, respectively, and FIG. 6 is an explanatory diagram of an embodiment in which a reading beam is provided in advance of a recording beam. Figure 7 (a), (b), Figure 8 (a), (b), (c)
are diagrams for explaining the principle of magneto-optical two hammers, respectively.
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Claims (10)

[Claims] (1) In a magneto-optical recording method in which information is recorded by irradiating light onto a magneto-optical recording medium, at the Nth recording (N=1, 2, 3
...) and the (N+1)th recording time, the direction of the recording magnetic field is reversed. (2) When recording a binary signal on a magneto-optical recording medium having first and second magnetization directions, two 2. The magneto-optical recording method according to claim 1, wherein information is recorded using different types of magnetization patterns. (3) Magneto-optical recording according to claim 1, characterized in that the direction of the recording magnetic field of the recording area is recorded on a magneto-optical recording medium corresponding to a plurality of divided recording areas. Method. (4) A reproducing light beam that precedes a recording light beam reproduces previously recorded data, and modulation of the recording light beam is determined based on the reproduced data. magneto-optical recording method. (5) The magneto-optical recording method according to claim 1, characterized in that reproduction of recorded data is confirmed by a reproduction light beam following a recording light beam. (6) The magneto-optical recording method according to claim 2, wherein the magnetization pattern has at least one magnetization reversal. (7) The magneto-optical recording method according to claim 2, wherein the binary signal is a binary signal obtained by modulating recording information using a predetermined modulation method. (8) The magneto-optical recording method according to claim 2, characterized in that a synchronization pattern is inserted every other one or more of the magnetization patterns. (9) If the magnetization pattern is composed of 2 bits on the recording medium and the direction of medium magnetization is the first direction when recording a binary signal (1-0 signal),
A “0” signal is represented by two first direction magnetized bits, and a “1”
” signal is represented by one bit magnetized in the first direction and one bit magnetized in the second direction, and when the direction of medium magnetization is in the second direction, the “0” signal is expressed in the second direction. The magneto-optical recording method according to claim 2, characterized in that the "1" signal is represented by two magnetized bits, and the "1" signal is represented by one magnetized bit in the first direction and one magnetized bit in the second direction. . (10) The magnetization pattern is set to 2 on the recording medium.
When recording a binary signal (1-0 signal), if the direction of medium magnetization is the first direction, a "1" signal is represented by two bits magnetized in the first direction. ,“
A “0” signal is represented by one first direction magnetization bit and one second direction magnetization bit, and if the medium magnetization direction is the second direction, the “1” signal is represented by a second direction magnetization bit. It is represented by two direction magnetization bits, and the “0” signal is expressed as the first direction magnetization bit 1.
3. The magneto-optical recording method according to claim 2, wherein the magneto-optical recording method is represented by one bit and one bit magnetized in the second direction.