JPS61214265A - Photomagnetic recording and erasing system - Google Patents

Abstract

PURPOSE:To make the overwriting of information possible by recording and erasing information on a pair of adjacent sectors alternately with a single light spot and a single optical head having an external magnetic field applying means. CONSTITUTION:Odd sector areas of a disc are set to the continuous erasing state and even sector areas are set to the continuous DC recording state, and an external applied magnetic field 6 is directed downward and the optical pulses of a laser 2 are modulated in accordance with a signal to write information on the area of sector number 1. Simultaneously with this writing, the external applied magnetic field 6 is directed upward and the continuous light of the laser 2 is irradiated in DC to execute the erasing operation of the area of sector number 2. If the rewrite of another information to a pair of areas of sector number 1 and sector number 2 is requested again, the erasing operation is performed for the area of sector number 1, and the recording operation is performed for the area of sector number 2. Thus, processing are performed alternately to make spurious overwriting possible.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a magneto-optical disk file device.

In particular, the present invention relates to a magneto-optical recording and erasing method suitable for enabling information overwriting.

[Background of the invention]

Conventionally, as examples of override methods for magneto-optical disks, Japanese Patent Application Laid-Open No. 58-14304 and Japanese Patent Application Laid-Open No. 58-14
As described in No. 307 and JP-A-58-14308, a soft magnetic material with a coercive force of 10 a or less is used as the recording material, and irradiation can be performed without changing the direction of the external bias magnetic field during recording and erasing. This method performs recording and erasing by changing the optical power and magnetic field strength. However, this method is inconvenient in that it imposes a large burden on the recording material and cannot be used for magneto-optical disks using general perpendicular magnetization films.

Another method is to provide two separate optical heads, one for recording and the other for erasing.
In this method, an access system and a signal processing system are required separately for each optical head, which increases the scale of the device and cannot be said to be an effective method.

[Purpose of the invention]

An object of the present invention is to record and erase information alternately between a pair of adjacent sectors using a single optical head having a single optical spot and an external magnetic field applying means (electromagnetic coil), thereby overwriting information. The object of the present invention is to provide a magneto-optical recording and erasing method that can realize the following.

[Summary of the invention]

In order to achieve the above object, the present invention first uses a magneto-optical disk in which one track (one round) is divided into an even number of sectors. Second, the initial magnetization directions of two adjacent sector areas of the magneto-optical disk are set in advance to be opposite to each other. For example, before supplying the disk, DC light pulses are continuously irradiated to the disk recording film (perpendicular magnetization film) so that the odd-numbered sector areas are magnetized upward and the even-numbered sector areas are magnetized downward. This can be dealt with by alternately inverting the numbers.

Information is recorded on such a magneto-optical disk in the first order. Now, consider a disk in which upward perpendicular magnetization is the magnetization direction in the unrecorded state, and odd-numbered sectors are magnetized upward and even-numbered sectors are magnetized downward. That is, in this state, the odd-numbered sector areas are in a continuous erasing state, and the even-numbered sector areas are in a continuous DC recording state. Let us now consider the case where information is written into the area of sector number 1. Magneto-optical recording corresponds to reversing perpendicular magnetization in a direction opposite to peripheral magnetization in response to an information signal. Therefore, information is written to sector number 1 by turning the externally applied magnetic field downward and modulating the optical pulse in accordance with the signal. At the same time, the direction of the externally applied magnetic field is reversed upward to the subsequent area of sector number 2, and continuous light is irradiated in a direct current manner to perform an erasing operation.

If rewriting with new information is requested for the pair area of sector numbers 1 and 2 again, the externally applied magnetic field is directed upward for the area of sector number 1, contrary to the above process. The old information is erased by irradiating it with continuous DC light, and the externally applied magnetic field is reversed downward and a light pulse modulated in accordance with the signal is irradiated to the subsequent area of sector number 2. Record information.

By performing the above processing alternately, although it is not an override in a complete sense, by introducing the concept of alternate sectors, it is possible to realize a pseudo override of record equal erasure.

Note that it is currently necessary to recognize the states of sector numbers 1 and 2, that is, in which sector information is recorded, and whether the magnetization direction is set upward or downward. In this method, one separate semiconductor memory module is provided for each disk used, and the current status of each sector is recorded.

That is, magnetization direction information and recording/erasing state information are always stored9. For example, the address of a semiconductor memory is
The memory contents are made to correspond to the track number and sector number, and the first operand contains magnetization direction information and the second
Recording/erasing status information is stored in the operand. A non-volatile memory is suitable as the memory module. In other words, since it is always used in pair with a disk, the memory contents must be preserved even if the memory module is removed from the file device. This point can be solved by having a backup battery or a large capacity capacitor in the module and charging it while the module is connected to the file device. moreover,
on the file device itself.

It is also possible to store memory modules that are not currently in use, and to constantly charge them from the file device while they are being stored. Further, if the disk itself is used in a format housed in a cartridge, it is also suitable to provide a memory module in the same cartridge.

In addition, a directory dedicated to storing the magnetization direction information of each sector is provided in a certain area of the magneto-optical disk, and the contents of the directory are transferred to the semiconductor memory upon initial startup after the disk is installed in the file device. When writing to a module and erasing records while the disk is in use,
The memory is used. When the use of the disk is finished, before removing the disk from the file device, the latest magnetization direction information currently stored in the memory is restored.

Rewrite the directory contents of the disk. This method has the advantage that it is not necessary to have a semiconductor memory paired with a disk, and it is sufficient to prepare it in the file device as a work memory.

Next, there is the problem of the time required to reverse the direction of an externally applied magnetic field, ie, magnetic field switching. A feature of magneto-optical disks is non-contact playback, which allows playback without the optical head coming into contact with the disk surface. To take advantage of this feature, the electromagnetic coil for applying an external magnetic field must also be installed at a distance that takes into account the vertical vibration of the disk. It is convenient to previously provide disc information, etc. in the form of uneven pits at the beginning of each sector of the disc. This region is called a header region, and it is necessary to perform magnetic field reversal while passing through this header region. By reducing the time constant of the electromagnetic coil and increasing the coil drive current, it is possible to keep the switching time within the header region transit time. If the electromagnetic coil has a switching time of one sector, it is preferable to pair every other sector rather than pairing two adjacent sectors. For example, by using sector numbers 1 and 3 as a pair and sector numbers 2 and 4 as a pair, it is possible to cope with the delay in magnetic field switching.

[Embodiments of the invention]

The present invention will be described below with reference to Examples.

FIG. 1 is a block diagram showing an example of a magneto-optical disk device embodying the present invention. In the figure, reference numeral 1 denotes a magneto-optical disk, on which a perpendicular magnetization film having a magneto-optic effect is formed. Recording, erasing, and reproducing magnetization information are performed as follows.

The light emitted from the semiconductor laser 2 is converted into a parallel beam by a coupling lens 3, and is made incident on a diaphragm lens 5 via a polarizing prism 4, where it is focused on the perpendicularly magnetized film of the disk 1 as a minute spot. When recording information, the drive current of the semiconductor laser 2 is modulated with the information signal to be recorded.

The temperature of the perpendicularly magnetized film on the disk 1 is locally increased by the heat of the optical pulse corresponding to the information. A perpendicularly magnetized film has the property of losing its magnetization when the temperature exceeds one Curie temperature. Therefore, when the magnetization of the magnetized film is lost, by applying a magnetic field in the opposite direction to the magnetization of the unrecorded part from the outside using the electromagnetic coil 6, only the part irradiated with light has the magnetization in the opposite direction. In other words, a magnetized domain is formed. In order to erase information that has already been written, simultaneously with the irradiation of light onto the disk 1, a magnetic field in the direction opposite to the magnetization direction of the recording magnetization domain is applied by the electromagnetic coil 6.

Information is reproduced using the magneto-optical effect represented by the Kerr effect.The Kerr effect is a phenomenon in which the polarization planes of incident light are slightly opposite to each other, corresponding to the upper and lower magnetization directions of a perpendicularly magnetized film. This is the effect of rotating.

The reflected light from the disk 1 whose polarization plane has been rotated is as follows.

The light passes through a diaphragm lens 5, is separated by a polarizing prism 4, and is guided to an analyzer 7. The analyzer 7 is an optical element that passes only a certain specific polarized light component. Therefore, due to the Kerr effect, when light whose plane of polarization has been rotated in accordance with the magnetization direction of the magnetized domain enters the analyzer 7, it is converted into a change in the amount of light. This change in light amount is converted into an electrical signal by a photodetector 8, and then amplified by an amplifier 9 to a desired level.

Since the signal light from the disc 1 contains noise due to defects in the disc 1, dust, etc., and fluctuations in the reproduction light, the level slice circuit 10 only extracts signals with amplitudes above a certain level. I am trying to output it. The signal digitized by the level slice circuit 10 is guided to a signal processing system and an address decoder 11. The address decoder 11 has a function of decoding the track number and sector number written in a part of the header.

Therefore, it is possible to always know the track number and sector number where the optical spot is currently located.

The address decoder 11 is also used in write-once optical discs and is well known, so details of its contents will be omitted.

The address information 12 is input to the recording/erasing controller 13. On the other hand, 14 is a semiconductor memory module, and the address bus of this module corresponds to the track number and sector number of the disk 1. By commands from the controller 13, magnetization direction information and recording/erasing state can be stored and rewritten at arbitrary addresses.

The direction in which the electromagnetic coil 6 is energized and the drive of the semiconductor laser 2 are also controlled by the controller 13 .

Next, a disk format for implementing the present invention will be described. FIG. 2 is an example of a disk format. The disk 1 is divided into an even number of sectors, and a header is provided at the beginning of each sector. The header contains sector marks, self-clock synchronization signals,
Contains track number and sector number. Information in these header areas is recorded as pits of unevenness information (phase structure). FIG. 3 is a diagram showing the magnetization direction and recording/erasing state of each sector. 21~ in Figure 3
24 indicates a header area provided at the beginning of each sector. Arrows in the data areas 31 to 34 of each sector indicate the magnetization direction of the perpendicularly magnetized film. Now consider the case where the magnetization direction is set to the state shown in FIG. 3 (,). Furthermore, consider the case where sector numbers 1 and 2° and sector numbers 3 and 4 are paired. As the contents of the memory addresses corresponding to sector numbers 1 and 3 in the memory module 14, magnetization direction information upward and an erased state are stored. Conversely, the contents of the memory addresses corresponding to sector numbers 2 and 4 are stored such that the magnetization direction is downward and that the recording state is present. Now sector numbers 1 and 2
The information recording command for the data area of the pair is issued by the upper cp.
Consider the case given by u.

In FIG. 3(b), data area 3 of sector number 1
It can be recognized from the content of the corresponding address of the memory module 14 that the magnetization direction of the magnet 1 is upward from the erased state.

Therefore, in the section of the data area 31, the direction of the external magnetic field is directed downward, and at the same time, a light pulse modulated in accordance with the information is irradiated to perform recording.In the section of the data area 32 of sector number 2, this is reversed. The direction of the external magnetic field is directed upward, and erasing is performed by irradiating DC light at the same time.

At the same time, the contents of the memory module address corresponding to sector number 1 are rewritten to indicate that sector number 1 is in a downward magnetization direction and in a recording state. The contents of the memory address corresponding to sector number 2 are rewritten to the effect that the magnetization direction is upward and that it is in the erased state.

Next, consider a case where a rewriting command to new information is given to the pair area of sector numbers 1 and 2. In FIG. 3(Q), contrary to the case of FIG. 3(b), an upward magnetic field and a DC
applying a light pulse to erase already recorded data; applying a downward magnetic field and a light pulse modulated in accordance with new information to the data area 32 of sector number 2;
In this case as well, the contents of the memory module 14 are changed in the same way as shown in FIG. 3(b).

To write new information to the same area again, the third
The process shown in Figure (b) will be executed.

In this embodiment, as shown in FIG. 1, one analyzer converts the rotation of the plane of polarization into a change in the amount of light, but there is no particular restriction on the signal detection method.

Therefore, the present invention can be practiced even with a differential detection method using two analyzers or a differential detection method using a 1/2 wavelength plate and a polarizing beam splitter.

〔Effect of the invention〕

According to the present invention, it is possible to override information on a magneto-optical disk using only a single optical head. In the present invention, two sector areas are used as a pair,
By always alternating the recording and erasing states, it becomes possible to overwrite information without waiting for the disk to rotate. Furthermore, since only one optical head is required, it is possible to downsize the file device and is an economical method.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a magneto-optical disk device for carrying out the present invention, FIG. 2 is a plan view of a magneto-optical disk divided into sectors, and FIG. 3 is a diagram showing the perpendicular magnetization direction on the disk and irradiation. FIG. 3 is a diagram showing the relationship between a light pulse and an external magnetic field. 1... Magneto-optical disk, 2... Semiconductor laser, 6.
... Electromagnetic coil, 7... Analyzer, 11... Address decoder. 13...Controller, 14...Memory module, 21-24...Header area, 31-34...Data 1st round

Claims (1)

[Claims] 1. In the magneto-optical recording and erasing method, which uses a perpendicularly magnetized film, records and erases information using a thermomagnetic effect, and reproduces information using a magneto-optical effect, the method is divided into an even number of pieces. has a sector structure, and has two adjacent sectors as a pair of information recording units, and a header area including at least a track number and a sector number is provided in advance as a concave-convex pit at the beginning of the sector, and a header area other than the header area is A magneto-optical disk having a data area is used, and a semiconductor memory is provided in which the perpendicular magnetization direction of the data area of the sector and the data area of the sector correspond to the track number and sector number. A magneto-optical recording/erasing method characterized in that the state of the sector is memorized, either recording or erasing, so that the state of the sector can be recognized. 2. In the magneto-optical recording/erasing method according to claim 1, the magnetization direction of the data areas of odd-numbered sectors is set upward, and the magnetization direction of the data areas of even-numbered sectors is set downward. , storing information to the effect that the odd-numbered sector is in an erased state and magnetization is upward in the operand portion of the address corresponding to the sector of the semiconductor memory;
It is also stored in the semiconductor memory that the even-numbered sectors are in a recording state and the magnetization is downward, and when recording information, a downward external magnetic field is applied to an odd-numbered sector area. At the same time, a laser light pulse modulated in accordance with the information is irradiated, and subsequent to the odd-numbered sector, an upward external magnetic field and a direct current laser light are irradiated to the adjacent even-numbered sector. A magneto-optical recording erasing method characterized by rewriting an operand in an address corresponding to the sector. 3. In the magneto-optical recording and erasing method described in claim 2, when rewriting data with new information, an upward external magnetic field is applied to odd-numbered sectors with downward magnetization in which information has already been recorded. , a magneto-optical recording/erasing method characterized by irradiating direct current laser light, and then irradiating upwardly magnetized even-numbered sectors with a downward external magnetic field and laser light pulses modulated in accordance with information. . 4. In the magneto-optical recording erasing method according to any one of claims 1 to 3, a series of record erasing processes performed on odd-numbered and even-numbered sector areas are performed on odd-numbered and even-numbered sector areas. A magneto-optical recording erasing method that is characterized by rewriting information using the same process by reversing the handling of even numbers. 5. In the magneto-optical recording/erasing method according to any one of claims 1 to 4, the semiconductor memory comprises:
It is characterized in that it can be attached to and removed from a magneto-optical disk file device in the form of a module, uses non-volatile random access memory (RAM), and one memory module corresponds to one magneto-optical disk. Magneto-optical recording erasure method. 6. In the magneto-optical recording and erasing method according to any one of claims 1 to 5, a directory that stores the magnetization direction of each sector area and whether it is in a recording or erasing state. After setting an area in a certain area of the magneto-optical disk and setting the disk in a file device, the contents of the directory are transferred to the semiconductor memory in the file device at initial startup, and the contents of the directory are transferred to the semiconductor memory in the file device when the disk is in use. The magnetization direction information of each sector is stored in the semiconductor memory each time, and when the disk is finished using and before it is removed from the file device, the directory area of the disk is rewritten with the contents of the semiconductor memory. Features a magneto-optical recording erasing method.