JPH01179246A - Magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize the high density and the preservation for a long time of a record by transferring and recording information by photoirradiation large in power after recording the information on an information recording plane having two magnetic layers by a magnetic head, and reproducing the information optically. CONSTITUTION:The information recording plane 4 is formed by a first magnetic layer 41 with a small coercive force and a high Curie temperature and a second magnetic layer 42 with a large coercive force and a low Curie temperature. When a light beam 50 large in power is projected from an optical head 2 after the information is recorded on the layer 41 by the magnetic head 5, a temperature on one spot on the plane 4 is increased, and the temperature of the layer 42 on that part exceeds the Curie temperature, then, the information on the layer 41 is transferred. And track width to be transferred goes to narrow width equivalent to the spot diameter of the beam 50. Also, at the time of reproduction, the information is read out optically by decreasing the power of the beam 50. In such a way, it is possible to realize the high density of the record and to preserve the record for a long period.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a data recording device for recording and reproducing data.
The present invention relates to a magneto-optical recording and reproducing device that magnetically and optically records and reproduces information.

(Prior Art) A magneto-optical disk device records information by irradiating a magnetically biased, focused laser beam onto a recording medium that has a magneto-optic effect, and also records information on a recording medium that has a magneto-optic effect. The recorded information is reproduced by detecting the change in the polarization state of the reflected light of the irradiated laser beam.In other words, it is possible to record extremely high information at the focused light spot size level. Furthermore, it is attracting attention as a device that can erase and re-record information by changing the magnetism of the bias magnetic field.

However, in conventional magneto-optical disk drives, in order to erase information, it is necessary to continuously irradiate the medium with focused light that generates a temperature sufficient to cause magnetization reversal by changing the polarity of the bias magnetic field. Therefore, erasing and re-recording information requires complex processing functions and a considerable amount of processing time. Such a re-recording function is completely inadequate. Furthermore, since the recording bit size is limited by the spot size of the focused light, even if the density is high, it cannot reach the layer density (short bit length) achieved by magnetic recording.

In order to solve these problems, during recording (re-recording), the medium is irradiated with a laser beam of high direct current power, and the bias magnetic field is modulated according to the data signal. There is a method called ``magnetic field modulation'' for recording information. This method requires high-speed switching of a large current in order to generate and modulate a magnetic field sufficient for recording using a magnetic field-generating electromagnet (coil) located relatively far from the medium surface.・It was extremely difficult to perform sufficient modulation (switching) to support high-density recording.

On the other hand, magnetic recording can be easily overwritten, and therefore information can be easily rewritten and lasts for a long time. However, on the other hand, the recorded information can be erased due to the presence of surrounding magnetic fields, etc. Cheap. Also, with recent technological advances, the recording density in the linear direction (bit length direction) has become extremely high, but the density is the same in the track width direction (track density) due to head width limitations and a drop in the reproduction signal level. It was not possible to open the can sufficiently as specified, and as a result, the record @i
The storage capacity (clean surface recording) is quite low compared to optical disk devices and magneto-optical disk devices. In particular, perpendicular magnetic recording, which is one of the density recording technologies in magnetic recording, has the potential to perform extremely high-density recording, but it has the drawback of not being able to obtain a sufficient signal level during readout. It is not possible to make full use of the recordability.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention, in other words, the purpose of the present invention is to provide a magneto-optical recording and reproducing device that improves the above-mentioned problems by optically reading out magnetic records without destroying them. There is a particular thing.

Means for Solving Problem L] The magneto-optical recording and reproducing apparatus of the present invention includes a Zo magnetic layer that magnetically records information by obtaining magnetization in the in-plane direction or perpendicular direction to the recording surface; The first magnetic layer has an axis of easy magnetization in the direction perpendicular to the surface and has a high coercive force. a record carrier having an information recording surface formed by laminating two magnetic layers;
a magnetic head for magnetically recording and reproducing information on the record carrier; and a magnetic head for detecting changes in magnetic light on the recording surface by receiving reflected light that is reflected when the record carrier is irradiated with focused laser light. an optical head; a means for recording and reproducing information in the tenth magnetic layer by the 4a magnetic head; means for transcribing and recording the information of;
and means for reading information on the second magnetic layer from reflected light generated by irradiating a second laser beam with the optical head while retaining the information transferred and recorded on the second magnetic layer. be done.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing a complete example of a magneto-optical recording/reproducing apparatus of the present invention. In the figure, a record carrier 3 has a recording surface 4 formed of two magnetic layers, and a magnetic head 5 is arranged between the recording surfaces 4. On the other hand, the optical head 2 may be configured to focus and irradiate a laser beam spot onto the information recording surface 4.

The positional relationship between the magnetic head 5 and the optical head 2 is such that the focused light spot traces the scanning area (track) on the recording surface 4 recorded or reproduced by the magnetic head 5 as the recording carrier 3 moves (rotates). It is arranged so that the light spot is irradiated on the same position, that is, on the same track as the foot track formed by the magnetic head 5. Also, the movement of the optical head 2 or magnetic head 5 in the cross-track direction (disk radial direction) (
For track access), it is necessary to move them together so as to maintain the above position relative to each other.
Details of such a mechanism will be omitted.

Note that the width of the scanned track by the magnetic head 5 is considerably wider than the track width placed by the optical spot, and therefore, the position of the optical spot (original head 2) in the track transverse direction with respect to the magnetic head 5 is magnetic head 5
y& may be varied within the range of 1-. ``Also, the track direction of the magnetic head 5 and the optical spot (original head 2), that is, the positional relationship between the front and rear, can be set arbitrarily to some extent.

When recording data on the record carrier 3, the recording signal generation circuit 14 receives recording data 101 from a host device, performs necessary modulation, and transmits the signal to the magnetic head drive circuit 12.

The magnetic head drive circuit 12 supplies a recording current to the magnetic head 5 according to the recording signal, and magnetically records information on the information recording surface 4. To reproduce this magnetically recorded information, the magnetization readout signal induced in the magnetic head 5 is amplified by the magnetic signal readout amplifier 13), and then processed by the magnetic recording signal readout circuit 15, as in a normal magnetic recording device. magnetic read data 102. Such magnetic recording and reproducing can be used for temporary recording of data.

However, as mentioned above, with magnetic recording alone, demagnetization, that is, distortion of the recording state, may occur due to external magnetic fields, etc.'jb)
Data storage stability is not necessarily sufficient.
Since the width of the magnetic head 50 is wide, the width of the recording track is wide and the track height cannot be increased very high. Therefore, in the present invention, the information recording m14 is formed between the first magnetic layer and the first magnetic layer on which magnetic recording is performed by the magnetic head 5. It is composed of two magnetic layers, a second magnetic layer that thermally transfers the magnetization information formed in the first magnetic layer, and the second magnetic layer thermally transfers the magnetization information recorded in the first magnetic layer by irradiation with focused light. The data is transferred to the layer with a narrow track width to achieve long-term data storage and high track density.

When turned on, the laser drive circuit 'Mr1 supplies a relatively large '1itt&' to the \ conductor laser 21 in the optical head 2, causing it to emit a large power laser beam. Note that the laser emission at this time does not have to be changed according to the data like in a general optical disk device, but it is good to have a constant DC intensity source. I will omit the details of tPeng's four-fold structure, but for example, collimating lens 2
Information is recorded by converting the laser beam into a diverging parallel laser beam from F21, passing through a half mirror 23 that separates the incident light and reflected light, and focusing the parallel laser beam with an objective lens 24. Since the light is irradiated onto a predetermined position on the surface 4, there is no blurring.

The temperature of the point on the information recording surface that is irradiated with the high-power focused light increases as described above, and the temperature of the second magnetic layer at that point rises to above the Curie point and is recorded in the first magnetic layer. magnetization information (pattern) is transferred. At this time, the temperature rise occurs only at the key points where the focused light is irradiated, so the track width where transfer occurs is extremely narrow, limited by the size of the focused light (spot diameter →).Such transfer is realized. In order to achieve this, the coercive force of the first magnetic layer is set to be relatively small so that magnetization reversal occurs easily by the magnetic head 5, whereas the coercive force of the second monolayer is set to be relatively small at room temperature. The temperature of the first magnetic layer is set to be considerably larger than that of the magnetic layer, and its temperature is set to be relatively low. A sufficiently high Chierry temperature needs to be selected.

In this way, the recording track formed by focused light irradiation is narrower than the track formed by the magnetic head, so the position of the magnetic head 5 with respect to the recording track formed by the focused light spot is set to have a rough wave. Also good. Further, the recording track density seen from the optical system is different from the track density seen from the magnetic head 5 (magnetic recording system).

As described above, since recording by the optical head 2 is performed in the form of transferring the magnetization pattern recorded by the magnetic head 5, the operation of erasing and re-recording (rewriting) recorded data is performed by the magnetic head 5 in the same way as simple recording. This is performed by recording and transferring by irradiating strong laser light.

- Reading of information recorded ancestrally (thermal transfer) is performed in the same way as in a general magneto-optical disk device. That is, with the transfer recording control signal 110 turned off/off, the laser drive circuit 4 supplies a relatively low level of Wa to the semiconductor laser 21, and the semiconductor laser 21 thereby emits a low power laser beam. When this low power laser beam is irradiated onto the information recording surface 4, it is recorded (
The polarization of the reflected light changes due to the Kerr effect or Faraday effect due to the transferred magnetization. When this reflected light whose polarization has changed is received by a split (or two-element) photodetector 26 through a polarization detection element 25 made of a 1/2 wavelength plate Wollaston prism, etc., a polarization change KG is detected. A current is output. By amplifying this current change by the magneto-optic signal read amplifier 10 and processing it by the read signal processing circuit 11, the information recorded in the second magnetic layer by transfer can be reproduced as magneto-optic read data 103.

Since this read operation is performed optically, even if the recording track width is narrow, problems such as the read signal level becoming extremely low and poor reproduction, which occurs in magnetic read, do not occur.

In addition, as mentioned above, the second magnetic layer has a high coercive force at room temperature, and desensitization due to external magnetic fields etc. does not occur.
, it is possible to obtain reliable business records that ensure long-term storage of high-quality data.

FIG. 2 is an explanatory diagram showing fermentation of the recording carrier 3.

In the figure, the record carrier 3 is composed of a transparent substrate 3o that transmits the original beam 50t irradiated by the optical head 2, and an information recording surface 4 consisting of a first magnetic layer 41 and a second magnetic layer 42. There is. Note that the light beam 50 can also be irradiated from the same 11III as the magnetic head 5, and in this case, the substrate 30 does not necessarily have to be transparent.

FIG. 3 is a characteristic diagram showing an example of the temperature characteristics of the coercive force of the first and second magnetic layers. Line A in the figure shows the temperature characteristics of the first magnetic layer 41, and line B shows the temperature characteristics of the second magnetic layer 42. Coercive force at room temperature (Hc
l) Set Fi to a relatively small value and select a material with a high Chierly point whose coercive force decreases little due to temperature rise.

Further, the magnetization direction may be horizontal to the recording surface, that is, in-plane direction, but since it is necessary to magnetize the second magnetic layer 42 in the perpendicular direction, the axis of easy magnetization is set perpendicular to the recording surface. M is preferable. Examples of the material for the first magnetic layer 41 include barium-7 elite, cobalt-
There is copper, etc.

On the other hand, the second magnetic layer 42 needs to remain unchanged when the first magnetic layer 41 is magnetized by the magnetic head 5, and preferably has a relatively large coercive force (Hc, ) at room temperature. Furthermore, when the temperature of the magnetic layer rises due to irradiation with the light beam 50 of high power, the coercive force of the first magnetic layer 41 (magnetization can be easily transferred) decreases rapidly due to temperature rise, reaching the Chierly point (Tct). ) is preferably relatively low, and a material having characteristics as shown by line B in FIG. 3 is used.

Further, in order to optically read out the recorded information (magnetization) by the Kerr effect or Alladay effect, which has an axis of easy magnetization in the perpendicular direction, it is preferable to use a material with a large Kerr effect or Faraday effect. As the material of the magnetic layer 42, for example, a magneto-optical recording material such as TbF@Co can be considered.

When recording information, the magnetic head 5 first magnetizes the ninth magnetic layer 41, but at this time, the second i-type M42 has a large coercive force (Hc), so it is magnetically The head 5 is not magnetized. In other words, the previous magnetization state is maintained. Therefore, in this state, new information recorded in the first i-pillar layer 41 by the magnetic head 5 can be read, but the second magnetic The magnetization state of the layer 42 remains the same as before, and only the old information can be read by the optical head 2. After this first magnetic layer 41 is recorded, a high power light beam is sent to the optical head 2 to read out the information. When the recording surface is irradiated, the temperature of the second magnetic layer 42 is higher than the Chierly point ('r,,), and the first magnetic layer 41
Recording is performed by transferring the magnetization of . The magnetization information transferred to the second magnetic layer 42 can be easily read by the optical head 2 as described above. - Since the magnetization of the first magnetic layer 41 may change in any way after the 42 km of the second magnetic layer is transferred, it is possible to record other information on another track (relative to the optical head). Other data may be continuously recorded by the magnetic head 5.

Through such a procedure, information can be easily replaced without requiring any special erasing operation.

[Effects of the Invention] As explained above, the present invention magnetically records information with a magnetic head on a recording carrier having an information recording surface with two magnetic layers having different characteristics, and then an optical head magneto-optical recording and reproducing technology that allows data to be rewritten without special erasing operations by transferring and recording magnetization information in row b1 using high-power light irradiation, and by making the transferred record optically readable. This has the effect of realizing the device.

Further, according to the present invention, it is possible to achieve a linear recording density comparable to magnetic recording while increasing the track density to a high density comparable to optical recording, thereby making it possible to realize a large-capacity recording device with an extremely high recording density.

Furthermore, since information recorded magnetically by the magnetic head can be read out directly by the magnetic head, there is also the effect that temporal data recording and updating can be easily performed.

Furthermore, since the information recorded by transfer is recorded on a magnetic layer having a high coercive force, the long-term storage stability of the information is also improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magneto-optical recording/reproducing device of the present invention, FIG. 2 is an explanatory diagram showing the structure of the record carrier, and FIG. 3 is a diagram showing the coercivity of the first and second magnetic layers. FIG. 3 is a characteristic diagram showing an example of temperature characteristics. DESCRIPTION OF SYMBOLS 1... Laser drive circuit, 2... Optical head, 3rd recording signal generation circuit, 15... Magnetic recording signal reading circuit, 41... First magnetic layer, 42
...'s2 magnetic layer.

Claims (1)

[Claims] A first magnetic layer that magnetically records information by obtaining magnetization in the in-plane direction or perpendicular direction to the recording surface, and a coercive force from the first magnetic layer having an axis of easy magnetization perpendicular to the recording surface. a second magnetic layer having a high Curie temperature and a low Curie temperature and a magneto-optical effect such as Kerr effect or Faraday effect; a magnetic head for recording and reproducing data; an optical head for detecting magneto-optical changes in the recording surface by receiving reflected light when the record carrier is irradiated with focused laser light; means for recording and reproducing information on the first magnetic layer; means for irradiating a first laser beam with the optical head to transfer and record the information on the first magnetic layer on the second magnetic layer; and means for reading out information on the second magnetic layer from reflected light generated by irradiating a second laser beam with the optical head while retaining the information transferred and recorded on the second magnetic layer. A magneto-optical recording and reproducing device.