JPH0322234A - Information recorder - Google Patents

Abstract

PURPOSE:To surely record information even though the width of a magnetic head is not made larger by performing the control of the tracking of the magnetic head with a tracking error signal detected by an optical head. CONSTITUTION:A light beam reflected by a magneto-optical disk 3 passes through an objective lens 28 again and photoelectrically converted by a photodetector in the optical head 2, which is not shown by a figure. A servo error detection circuit 12 obtains a focusing error signal and the tracking error signal from a photoelectric signal. The tracking of the magnetic head 1 is performed by generating a control signal from the tracking error signal obtained by the servo error detection circuit 12 in the AT servo circuit 14 of the magnetic head and transmitting it to the head 1. Then, information is recorded by transmitting an information signal 9 to the magnetic head 1 through a modulation circuit 10 and impressing modulated magnetic field from the head 1 on the disk 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an information recording device that records information on a magnetic recording medium using the interaction between light and magnetism. [Prior Art] Examples of the above-mentioned devices include magneto-optical disk devices. Magneto-optical disk drives are attracting attention because of their large storage capacity and the ability to erase and rewrite. Further, studies are being conducted on overwriting to further increase the data transfer speed and on increasing storage capacity.

The Saiichi barlight method involves a magnetic field modulation method that modulates an external magnetic field according to recorded information while irradiating a constant laser power, and applies it to the medium to reverse the magnetization of the recording layer and form a pit. , while applying a constant external magnetic field, modulate the power of a binary laser corresponding to recording and erasing according to the recorded information and irradiate it to the medium, reversing the magnetization of the recording layer and forming a bit. There is a light modulation method.

However, in the magnetic field modulation method described above, because the distance between the magnetic head and the recording layer is long, it is difficult to modulate a large magnetic field at high speed and apply it to the medium. In addition, in principle, the shape of the bit formed is an arrow feather shape, which causes problems with edge fluctuations and unerased parts, making it difficult to record the bit length.

Even with the optical modulation method, there are problems with unerased data and a decrease in the C/N ratio, and pit length recording is also difficult.

Furthermore, since a power of 3 gM is required for recording, erasing, and reproducing, controlling the semiconductor laser was complicated. on the other hand. IBM Technical Disclosure B
uth etin)V o 1. 1 6, No-
1 7 December1973, P23ft
5-2366 uses a 2MtIlj iron oxide disk with a different coercive force. First, a conventional magnetic transducer records tracks in a conventional pattern on the storage transfer layer with a low coercive force, and then the narrow part of the track is recorded. A method has been proposed that uses a laser light source in the main memory layer with high coercive force and records data using the conventional thermomagnetic transfer process. In this method, information is read out by transferring information from the main storage layer to the storage transfer layer using a conventional magnetic transducer.

Also,. In JP-A No. 63-276731, Co
-A proposal for recording information on a disk with a two-layer structure of a Cr alloy thin film and a Tb-Fe thin film by recording with a magnetic head and transferring it with an optical head, and reproducing information using an optical head. is being done.

If such a method is used, unerased data will be reduced and pit length recording will become easier.

[Problems to be Solved by the Invention] On the other hand, tracking control is performed in general information recording devices, but in the above-mentioned Japanese Patent Laid-Open No. 63-276731, tracking control is achieved by widening the width of the magnetic head. It is explained that it is no longer necessary. However, unnecessarily increasing the width of the magnetic head not only hinders the miniaturization of the device but also increases power consumption. Conversely, if the width of the magnetic head is suppressed, there is a problem in that when a large tracking error occurs, a discrepancy occurs in the scanning positions of the magnetic head and the optical head on the medium.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide an information recording device that can reliably record information without increasing the size of the magnetic head.

[Means for Solving the Problems] The above object of the present invention is to provide an apparatus for recording information on a magnetic recording medium having tracks using five magnetic heads and an optical head, in which a track error signal is detected in the optical head. This can be accomplished by providing a means and using this tracking error signal to control the tracking of the magnetic head. Further, the above information recording apparatus includes, for example, a magnetic head that applies a magnetic field modulated according to information to a magnetic recording medium having tracks, and an optical head that irradiates a focused light beam onto the tracks of the medium. , a first tracking means that is mounted on the optical head and moves the irradiation position of the light beam in the direction across the track; and a second tracking means that moves the magnetic head and the optical head together in the direction across the track. and means for detecting a track error signal using the light beam, and a control circuit that feeds back the track error signal detected by the detection means to the first and second tracking means to perform tracking control. [Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the information recording device of the present invention. In FIG. 1, l is a perpendicular magnetic head, 2 is an optical head, 3 is a magneto-optical disk, 4 is a substrate, 5 is a protective and interference layer, 6 is a recording magnetic layer, 7 is a recording auxiliary magnetic layer,
8 is a protective layer. FIG. 2 shows the coercive force characteristics with respect to temperature of these magnetic layers. A curve 9 shows the characteristics of the recording-assisting magnetic layer 7. In other words, the recording assisting magnetic layer 7 has a small coercive force Hc at room temperature and a high Curie temperature Tc+. On the other hand, curve 10 shows the characteristics of the recording magnetic layer 6, which has a larger coercive force Hat at room temperature and a lower Curie temperature T (4) than the recording auxiliary layer 7. ,.

, is the compensation point temperature of the magnetic layer 7.

The magneto-optical disk 3 has tracks extending in the direction of arrow A in FIG. This track is constituted by a group formed in advance on the substrate 4 or a prepid for sampling servo. Then, the magneto-optical disk 3 is similarly moved in the direction of arrow A by means not shown. The optical head 2 has a built-in semiconductor laser as a light source. This semiconductor laser is controlled by a laser drive circuit l1 so as to emit light beams of different intensities during recording and reproduction. The light beam emitted from the semiconductor laser is focused into a spod shape by the objective lens 28, and is irradiated onto the magnetic layer of the disk 3 from the substrate 4 side. The spod diameter on the magnetic layer is about 0.5 to IILm. The light beam reflected by the disk 3 passes through the objective lens 28 again and is photoelectrically converted by a photodetector (not shown) in the optical head 2. Then, the servo error detection circuit 12 obtains a focus error signal and a track error signal from this photoelectric signal. As a method for detecting these error signals, for example,
Well-known methods such as those described in No.-56578 can be used. The above error signal is the AF of the optical head.
(autofocusing) and AT (autotracking) are input to the servo circuit l3, and a control signal is generated and sent to the optical head. In accordance with this control signal, the optical head 2 moves the objective lens 28 in the optical axis direction and in the direction perpendicular to the optical axis (direction B) using a lens actuator (not shown), and AF and AT are performed. On the other hand, the vertical head L is provided on the opposite side of the disk 3 from the optical head 2, and scans a position slightly ahead of the optical spod on the track being scanned by the optical spod. . The distance between these heads must be at least such that the range affected by heat from the optical spod and the range affected by the magnetic field from the perpendicular magnetic head do not overlap. Tracking of the magnetic head l is performed by creating a control signal in the AT servo circuit l4 of the magnetic head based on the track error signal obtained by the aforementioned servo error detection circuit l2, and sending this to the magnetic head l. At this time, the tracking error signal may be passed through a low-pass filter and the tracking control of the magnetic head 1 may be performed using only the low frequency component thereof. Information is recorded by sending the information signal 9 to the magnetic head 1 after being subjected to an error correction coat etc. by the modulation circuit 10, and applying a magnetic field modulated according to this signal from the magnetic head 1 to the disk 3. It is done. This recording process will be explained in detail using Figures 3 and 4. In FIGS. 3 and 4, (a) is a schematic sectional view of the magneto-optical disk, and (b) is a plan view.

In FIG. 3(a), first, using a perpendicular magnetic head l,
The magnetic field is modulated according to the recorded information. At this time, the maximum magnitude of the absolute value of the magnetic field on the magnetic layer is between the recording auxiliary magnetic layer (hereinafter referred to as the auxiliary layer) 7 and the recording magnetic layer (hereinafter referred to as the recording layer) 6 at room temperature. If the respective coercive forces are set to appropriate values between HC1 and Hc2, pits are formed in the auxiliary layer 7 as perpendicular magnetic domain arrays depending on whether they are directed upward or downward, according to the modulation of the magnetic field. However, since the strength of the applied magnetic field is less than the coercive force in the recording layer 6, it is not affected and the previous state is maintained.

The length of the bit in the direction parallel to the track by the perpendicular magnetic head can be on the order of a sub-micron, making it possible to increase the linear density compared to conventional pits recorded by an optical head. In addition, the width in the direction perpendicular to the tracks can be set to several to ten or more tracks, so that the tracking accuracy required of the perpendicular magnetic head can be relaxed.

This makes it possible to track the magnetic head using only the low frequency component of the tracking error signal obtained by the optical head as described above.

In FIG. 3(b), 19a to 19e each indicate a track, the width of which is 1 to 2 ILm. The bits recorded by the perpendicular magnetic head are magnetic domain arrays shown by solid lines. Assuming that the track to be recorded is 19c, the magnetic domain array is centered around 19c and spans several to ten tracks, overwriting the previous data.

After recording the magnetic domain array with the perpendicular magnetic head 1 in this manner, the spod 20 of the optical head 2 scans over a desired track 19c as shown in FIG. Then, the laser drive circuit 11 controls the light intensity to rotate the disk so that the temperature rise in the magnetic layer at this time becomes an appropriate temperature between the Curie temperatures Tct and Tc2 of the auxiliary layer 7 and the recording layer 6, respectively. Control according to the number. Then, the desired track 19 of the recording layer 6 heated to the Curie temperature TC2 or higher is heated by the optical spod 20.
In c, the previously recorded information is erased due to the magnetization disappearing.

Then, when the optical spod passes and the heat drops below the Curie temperature TC2, magnetization corresponding to the magnetization of the auxiliary layer 7 appears. That is, the magnetic domain array corresponding to the magnetic domain array of the auxiliary layer 7 is transferred to the diagonally shaded area of the recording layer 6 in FIG. 4(b), and information is written.

Here, as described above, the auxiliary layer 7 has a compensation point above room temperature, and the coercive force becomes large at the temperature during transfer, so that stable transfer is performed. The final pit shape recorded in this way is approximately square. The length of the pit in the direction parallel to the track is determined by the perpendicular magnetic head, and the width in the direction perpendicular to the track is determined by the optical spod of the optical head, which is 0.5 to 14 microns.
It will be around m.

On the other hand, information is reproduced by scanning a desired track with an optical spod of an optical head. At this time, the intensity of the optical spod is controlled by the laser drive circuit 1l so that the temperature of the magnetic layer does not become higher than the Curie point temperature c2 of the second layer. The reflected light from this optical spod is modulated in its polarization state by magneto-optical effects such as the Kerr effect, Faraday effect, and circular dichroism effect, and is converted into an intensity change by the analyzer, which is then detected by the aforementioned photodetector. Light is received.

The output of this photodetector is sent to the information reproducing circuit 15 shown in the first diagram, and a reproduced signal l6 is output.

Also, the temperature at the intersection of curves 17 and 18 shown in FIG.
If wo is the temperature of the magnetic layer during recording, T wo and Tc
It may be between I and below Two, which is the temperature of the magnetic layer during reproduction.

The power of the semiconductor laser for recording and reproducing using this method can be binary. In addition, the recording on the auxiliary layer by the magnetic head may be overwritten as described above, or in order to eliminate the effect of unerased data, after being transferred by an optical spod, the recording by the same magnetic head or a second magnetic head may be performed. It may be erased by

FIG. 5 is a schematic diagram illustrating another embodiment of the present invention. In FIG. 5, the same members as in FIG. 1 are denoted by the same reference numerals, and detailed explanations will be omitted.

In this embodiment, the magnetic head l and the optical head 2 are integrally held by the same support part 2l. and,
This support portion 2l is movable in a direction across the track (direction B) by a near motor (not shown), and constitutes a coarse tracking mechanism.

The focus error signal and track error signal detected by the servo error detection circuit l2 are input to the AF/precision AT servo circuit 22, and the lens actuator moves the objective lens 28 in the optical axis direction and in the direction perpendicular to the optical axis (B direction> AF and AT are performed by moving the lens to .

On the other hand, the track error signal output from the servo error detection circuit l2 is also input to the coarse AT servo circuit 23,
Rough tracking is performed by driving the linear motor according to this signal and moving the support portion 2l.

In this way, in this embodiment, rough tracking control for a desired track is performed by moving the magnetic head and the optical head together in accordance with the tracking error signal. At the same time, the lens actuator mounted on the optical head is driven according to the tracking error signal, and precise tracking control is performed so that the optical spod accurately follows the desired track. In addition, in this embodiment, a low-pass filter is provided between the servo error detection circuit l2 and the coarse AT servo circuit,
Using only the low frequency component of the track error signal, the support unit 2
It is also possible to drive 1.

FIGS. 6 and 8 show other configuration examples of magneto-optical disks used in the present invention, respectively, and FIG. 8 shows the coercive force characteristics of each layer with respect to temperature in these disks. FIG. 6 shows the auxiliary layer 7 of the structure of the magneto-optical disk shown in FIG.
An exchange force adjusting layer 24 is arranged between the main recording layer 6 and the main recording layer 6. Coercive force HC3 and Curie temperature TC of this layer at room temperature
3 has a characteristic like the curve 26 in FIG. This layer is magnetized in the in-plane direction at room temperature, and when the temperature rises due to the power of the optical spod during recording, it either has perpendicular magnetization that is the same as the direction of magnetization of the auxiliary layer 7, or the magnetization disappears. . This serves to weaken the exchange coupling force between the auxiliary layer 7 and the main recording layer 6 at room temperature. Therefore, the strength of the magnetic field during recording can be lowered to the HCI side. In FIG. 7, a reproducing layer 25 is further arranged between the recording layer 6 and the protective/interference layer 5 having the structure shown in FIG. As mentioned above, the Kerr rotation angle due to the Kerr effect during reproduction is larger for a magnetic layer with a higher Curie temperature. For that reason,
The coercive force HC4 and Curie temperature TC4 of the reproducing layer 25 have characteristics as shown by a curve 27 in FIG. This reproducing layer 25 is heated by the recording layer 6 due to the exchange coupling force with the recording layer 6 at a temperature increased by the power of the optical spod during reproduction.
Perpendicular magnetization corresponding to the magnetization of the pit appears. Since most of the light reflection during reproduction is affected by the reproduction layer 25,
The Kerr rotation angle becomes larger than that at the time of reflection on the recording layer 6.

Up to this point, the characteristics of the auxiliary layer 7 and the recording layer 6 are that, as shown in FIG. 2, the auxiliary layer 7 has a compensation point above room temperature (curve 9), and the recording layer 6 has no compensation point (curve 10). Although the case has been described above, the configuration shown in FIG. 6 or 7 may have the characteristics shown in FIGS. 9 to 11. Here, FIGS. 9, 10, and 11 show, respectively, that neither the auxiliary layer 7 (curve 9') nor the main recording layer 6 (curve 10) has a compensation point, and that the auxiliary layer 7 (curve MA9'') has no compensation point. The recording layer 6 (curve 10') does not have a compensation point, but the recording layer 6 (curve 10') has a compensation point, and the auxiliary layer 7 (curve 9) and the recording layer 6 (curve 10') both have a compensation point.

As a specific material for each layer of the magnetic layer group, a non-quality alloy made of a combination of one or more of each of transition metals and rare earth metals can be used. For example, transition metals are mainly Fe, Co, Ni, ff1 earth metals are mainly G
There are d, Tb, Dy, Ho, Nd, and Sm. Typical combinations are T b Fe Co , G d
T b Fe , GdFeCo, GdTbFeCo
, GdDyFeCo, etc. In addition, the material of the auxiliary layer is Co-Cr based, Ba-Ferr
ite series, MnBi series. It may be a magnetic material such as iron oxide type, Co-tope iron oxide type, Cr02 type, Ni-Co type, Fe-Ni-Co type, or Heusler alloy such as PtMnSb. Further, the auxiliary layer 7 may be a magnetic layer having in-plane magnetization as shown in FIG. In this case, a longitudinal magnetic head is used for recording.

The substrate 4 is made of glass, polycarbonate (PC), polymethyl methacrylate (PMMA), or other plastic material, and may be thick and hard, or thin and flexible.

The present invention can be applied in various ways in addition to the embodiments described above. For example, although a magneto-optical disk has been described in the embodiment, a card-shaped or tape-shaped medium can also be used.

Furthermore, the present invention is not limited to devices that use the process described in the embodiments, but can also be applied to devices that use other processes (for example, the above-mentioned magnetic field modulation method) as long as the device performs recording by the cooperation of a magnetic head and an optical head. However, it is possible to apply all of them.

[Effects of the Invention] As explained above, the present invention provides a device for recording information using a magnetic head and an optical head, in which tracking control of the magnetic head is performed using a tracking error signal detected by the optical head. Therefore, information can be recorded reliably without increasing the magnetic head's amplitude. Therefore, according to the present invention, it is possible to easily downsize the device and prevent power consumption.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention. FIG. 2 is a diagram showing the characteristics of a magneto-optical disk used in the present invention. 5 is a schematic diagram illustrating another embodiment of the present invention; FIGS. 6 and 7 are schematic cross-sectional diagrams illustrating other configuration examples of magneto-optical disks used in the present invention, respectively; 8 to 11 are diagrams showing the characteristics of the magneto-optical disk used in the present invention, respectively, and FIG. 12 is a schematic diagram showing the state of magnetization when an in-plane magnetization film is used as the auxiliary layer. l...Magnetic head 2...Optical head 3...Magneto-optical disk l2...Servo error detection circuit 1 3-...AF, AT servo circuit of optical head l4...
・AT servo circuit 28 of magnetic head...1 port for objective lens? t 冫 1 え■ (t-i kichi j 2) ≦ko l issue"i7:l 竃b口U'wa

Claims (4)

[Claims] (1) In an apparatus for recording information on a magnetic recording medium having tracks using a magnetic head and an optical head, the optical head has a means for detecting a track error signal, and the track error signal is used to record information on a magnetic recording medium. An information recording device characterized by performing tracking control of a magnetic head. (2) The information recording device according to claim 1, wherein tracking control of the magnetic head is performed using a low frequency component of the tracking error signal. (3) a magnetic head that applies a magnetic field modulated according to information to a magnetic recording medium having tracks; an optical head that irradiates a focused light beam onto the tracks of the medium; a first tracking means for moving the irradiation position of the beam in the direction across the track; a second tracking means for moving the magnetic head and the optical head together in the direction across the track; An information recording device comprising means for detecting an error signal, and a control circuit for feeding back the track error signal detected by the detecting means to the first and second tracking means to perform tracking control. (4) The information recording device according to claim 3, wherein the control circuit feeds back only the low frequency component of the tracking error signal to the second tracking means.