JPH03230346A - Overwrite type magneto-optical disk device - Google Patents

Abstract

PURPOSE:To improve the quality and reliability of an overwrite type magneto- optical recording device by arranging a compensating magnetic field impressing means and a compensating magnetic field adjusting means for a modulating magnetic field magnetic head to compensate a leaked magnetic field from an actuator. CONSTITUTION:An optical head 4 is arranged so as to continuously irradiate a required and position-adjusted laser spot to an magneto-optical recording medium 3 rotated at high speed and driven by the actuator 40 so that its focus is adjusted. The modulating magnetic field magnetic head 5 is opposed to the optical head 4 with interposed the medium 3 and arranged adjacently to the medium 3. The head 5 impresses a compensating magnetic field adjusted so as to compensate a leaked magnetic field from the actuator 40 to the medium 3 by means of the compensating magnetic field impressing means 1 and the compensating magnetic field adjusting means 2. Consequently, the quality of recording information is improved without generating the operation instability of the head 5 and the deterioration of service life.

Description

[Detailed Description of the Invention] [Summary] For the purpose of improving the recording signal quality (C/N) in a low modulation magnetic field region with respect to an overwrite type magneto-optical disk device, a magneto-optical disc device is provided that is rotatable at high speed. a recording medium, an optical head that is arranged to continuously irradiate a required laser spot whose position is adjusted on the magneto-optical recording medium and is driven for focus adjustment by an actuator; a modulating magnetic field magnetic head facing the optical head and disposed close to the magneto-optical recording medium; a compensation magnetic field applying means disposed so as to compensate for a leakage magnetic field from the actuator; and a compensation magnetic field applying means. The overwrite type magneto-optical disk device is configured to include at least compensation magnetic field adjusting means for adjusting the magnetic field generated by the overwrite type magneto-optical disk device.

[Industrial application field]

The present invention relates to an overwrite type magneto-optical disk device, in particular,
The present invention relates to the configuration of an overwrite type magneto-optical disk device that improves the quality (C/N) of recording signals by compensating for leakage magnetic fields from magnets used in actuators that perform optical spot control such as focus adjustment of optical heads.

(Prior Art) Magneto-optical disks are characterized by being rewritable and are expected to have a promising future and are being developed.

- For boat fishing, as described in Japanese Patent Application Laid-Open No. 63-273242, first erase the entire track or one track at a time, and then erase the data while applying a constant magnetic field for writing.
Information is written using a laser beam modulated with a recording signal. That is, in this case, when rewriting data, it is necessary to perform the erasing and writing operations twice, which has the disadvantage that the transfer speed of the recording device becomes slow.

Therefore, in recent years, progress has been made in the development of so-called magneto-optical disk devices of the overwrite type, in which rewriting can be completed in one operation, as is normally done in magnetic disk devices.

For example, FIG. 5 is a diagram showing an example of the configuration of a conventional overwrite type magneto-optical disk device.
This is an example described in No. 9. To briefly explain the operation according to the figure, continuous light emitted from the semiconductor laser 100 is turned into parallel light by the collimating lens 101, and the polarizing beam splitter 121... The magneto-optical recording medium 103 passes through the mirror 120 and the condensing lens (collimating lens) 114.
narrowed down to. The reflected light reflected by the magneto-optical recording medium 103 is passed through a collimating lens (condensing lens') 114. Mirror 120. reflected by the polarizing beam splitter 121,
Polarizing beam splitter 122, convex lens 1231, cylindrical lens 124. Focus error detection and tracking error detection are performed in the optical system that reaches the photodetector 125. In addition, when reading out a recorded signal, the light reflected by the polarizing beam splitter 122 is split into two optical paths by the polarizing beam splitter 130 and is sent to the photodetectors 131 and 13.
2 performs differential detection.

On the other hand, the focus error signal is fed back to an actuator 140 that includes a magnet, and drives and controls the condensing lens (collimating lens) 114 in the optical axis direction so as to always focus on a predetermined position.

That is, with the above configuration, the power of the laser beam irradiated from the optical head is kept constant.

On the other hand, the modulated magnetic field modulated by the recording signal is transmitted to the magnetic head 105.
This makes it possible to perform so-called overwriting, in which an electric current is applied to the magneto-optical recording medium 103 and recorded information is rewritten in one operation.

However, in this case, the magnet used in the actuator 140 generates a certain magnetic field in one direction, for example, upward, which adversely affects the modulating magnetic field applied to the magneto-optical recording medium 103. affect

Figure 6 is a diagram explaining the compensation operation of the modulated magnetic field of the conventional device.
is the net modulated magnetic field applied to the magneto-optical recording medium 103 by the modulated magnetic field (after compensation).

The vertical axis of the figure is the magnetic field, and the horizontal axis is time. In the figure, H5 is the leakage magnetic field from the actuator, H, -H.

is the peak value of the modulated magnetic field. In order to compensate for (cancel) the leakage magnetic field, the magnetic head 105 generates an asymmetrical modulated magnetic field as shown in FIG. , as shown in the same figure (b)! A symmetrically compensated demodulated magnetic field is applied to the magneto-optical recording medium 103 to stabilize the rewriting operation.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, in addition to the signal current for generating a modulation magnetic field, a compensating magnetic field is applied to a very small magnetic head, that is, an extremely thin coil winding. It is necessary to flow an extra bias current to generate a bias magnetic field, and there are serious problems such as unstable operation due to heat generation in the coil and shortened lifespan of the magnetic head, and a solution is needed.

[Means to solve the problem]

The above problem is solved by a magneto-optical recording medium 3 that is rotatably provided at high speed, an actuator 4 that is arranged so as to continuously irradiate a required laser spot whose position is adjusted on the magneto-optical recording medium 3, and The optical head 4 is driven for focus adjustment by the optical head 4, and the optical head 4 is opposed to the optical head 4 with the magneto-optical recording medium 3 interposed therebetween.

and a modulating magnetic field magnetic head 5 disposed close to the magneto-optical recording medium 3, a compensating magnetic field applying means 1 disposed to compensate for the leakage magnetic field from the actuator 40, and the compensating magnetic field applying means l. This problem can be solved by an overwrite type magneto-optical disk device which is equipped with at least compensation magnetic field adjustment means 2 for adjusting the magnetic field caused by the overwrite method.

[Function] As described above, in the device of the present invention, the compensation magnetic field is not generated by passing a bias current through the coil of the modulating magnetic field magnetic head 5, but by using the separately provided compensation magnetic field applying means 1 and the compensation magnetic field. Since the adjustment means 2 adjusts to compensate and cancel the leakage field ut from the actuator 40, it does not cause unstable operation or deterioration of the life of the magnetic head 5 for variable By4 magnetic field, and improves the quality of recorded information. becomes possible.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, numeral 3 denotes a magneto-optical recording medium formed on a polycarbonate resin plate, for example, a thin film made of TbFeCo.

Reference numeral 9 denotes a spindle motor for rotating the magneto-optical disk on which the magneto-optical recording medium 3 is formed at high speed. Reference numeral 4 denotes an optical head mainly composed of a condensing lens (collimating lens) and an actuator 40, and the actuator 40 includes a magnetic drive magnet for adjusting the focal position of the condensing lens (collimating lens). Reference numeral 5 denotes a magnetic head for modulating magnetic field, which is formed on the magneto-optical recording medium 3.

For example, several μm to several 1 μm with a protective film such as SiO□ in between.
It floats so that there is a minute gap of 0 μm,
It is connected to the slider by a gimbal spring and further connected to a magnetic head drive mechanism 6 to be driven. 1 is a compensation magnetic field applying means, for example, a small Sm-
A permanent magnet 2 such as Co is used to adjust the front, rear, left and right positions of the compensation magnetic field applying means 1, and a magnetic head 5 for modulating magnetic field.
For example, 1, for adjusting and controlling the magnitude of the compensation magnetic field (2), which is formed on the magneto-optical recording medium 3 by adjusting the height from
・It is a multi-axis position control mechanism equipped with an arm. 7 is the base of the entire device, and 8 is a cover.

In order to simplify the drawings, illustrations and explanations of parts not directly related to the present invention, such as light sources and optical systems, are omitted.

In the overwrite type magneto-optical disk centering, the rewriting operation is performed using the high speed j field of the magnetic head 5 for modulating magnetic field, so the size of the magnetic head 5 is designed to be as small as possible. In this example, a soft magnetic material such as 0.3 mm MnZn flight is used as the magnetic material.Therefore, even if there is a leakage magnetic field from the surroundings, even if it is minute, the small magnetic head will collect the magnetic flux. This will greatly affect the rewriting operation.The coil diameter of the magnetic head is approximately 0.15 mm.
.

The coil wire diameter is 508 mm and the number of turns is 40 turns.

On the other hand, as described above, the actuator 40 uses a magnetic drive magnet that adjusts the focal position of the condenser lens, and the leakage magnetic field H from the magnet on the magneto-optical recording medium
3 is estimated to reach around 1000e. Normally, the magnetic head 5 for modulating magnetic field modulates at about ±3000e, but if you try to modulate at a higher speed and with a smaller magnetic field, the influence of this leakage magnetic field is extremely serious, as described in the conventional example. However, in the present invention, the compensating magnetic field applying means 1 and the compensating magnetic field adjusting means 2 are adjusted to compensate for the leakage magnetic field HL from the actuator 40 on the magneto-optical recording medium 3. A compensating magnetic field H6 (-H5) is applied.

Figure 3 is a diagram explaining the compensation operation of the modulated magnetic field of the device of the present invention, in which (a) shows the modulated magnetic field (no compensation magnetic field), (b) shows the compensated magnetic field, and (c) shows the modulated magnetic field. (With compensation magnetic field)
It is. Note that the vertical axis represents the magnetic field, and the horizontal axis represents time.

If a symmetrical modulated magnetic field is applied to the magneto-optical recording medium 3 by the modulated magnetic field magnetic head 5, a leakage magnetic field 11. [Indicated by the broken line in the figure (A)] Therefore, as shown in the figure (A), the effective modulating magnetic field becomes asymmetric, making stable rewriting operation difficult.

Therefore, as shown in the same figure (b), the leakage magnetic field I+,
A compensating magnetic field IL, (-ut) in the opposite direction is applied.

As a result, as shown in the same figure (c), the magneto-optical recording medium 3
The effective modulating magnetic field becomes symmetrical, enabling stable rewriting operations, and thus improving recording signal quality.

FIG. 4 is a diagram showing the relationship between C/N and magnetic head modulation magnetic field, where the vertical axis is C/N (recording signal quality) and the horizontal axis is the magnetic head modulation magnetic field. In the figure, A shown by a solid line is a case where overwrite writing is performed by the apparatus according to the embodiment of the present invention, and it can be seen that the recorded signal quality is extremely stable not only in a high modulation magnetic field but also in a low modulation magnetic field. On the other hand, B shown with a broken line does not perform any magnetic field compensation for the leakage magnetic field H5,
In other words, this shows for comparison the case where the rewriting operation is performed with an asymmetric effective modulation magnetic field as shown in (a) in Figure 3, and a large C// N was obtained, but the C/N rapidly deteriorated on the low magnetic field side, making it difficult to use as a device with high reliability.

FIG. 2 is a diagram showing another embodiment of the present invention.

In this example, a compensation magnetic field applying means 1 is arranged between a magneto-optical disk forming a magneto-optical recording medium 3 and an optical head, and is provided on the opposite side from the embodiment shown in FIG. 40, the leakage magnetic field IIL can be compensated for with a small compensation magnetic field. However, in this case, it is necessary to provide an opening to ensure the optical path of the irradiated laser beam.

In the above embodiment, a permanent magnet is used as the compensation magnetic field application means 1, and a multi-axis position control mechanism equipped with an arm is used as the compensation magnetic field adjustment means 2, but the present invention is not limited to this. Compensating magnetic field adjusting means 2
Alternatively, the current control device for controlling the electromagnet current may be used.

The embodiments described above are merely examples, and it goes without saying that preferred materials and configurations, or combinations thereof, may be used as long as they comply with the spirit of the present invention.

[Effects of the Invention] As explained above, in the device of the present invention, the compensation magnetic field is not generated by passing a bias current through the coil of the modulating magnetic field magnetic head 5, but by using a separately provided compensation magnetic field applying means l. Since the leakage magnetic field I+ from the actuator 40 is adjusted to be compensated for and canceled by the compensation magnetic field adjusting means 2, the overwrite light is prevented from causing unstable operation or deterioration of the life of the modulating magnetic field magnetic head 5. This greatly contributes to improving the quality and reliability of magnetic recording devices.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing another embodiment of the invention, Fig. 3 is a diagram illustrating the compensation operation of the modulated magnetic field of the device of the present invention, and Fig. 4 is a diagram showing an embodiment of the present invention. A diagram showing the relationship between the C/N and the modulated magnetic field of the magnetic head. FIG. 5 is a diagram showing an example of the configuration of a conventional overwrite type magneto-optical disk device. FIG. 6 is a diagram explaining the compensation operation of the modulated magnetic field of the conventional device. It is. In the figure, 1 is a compensation magnetic field applying means, 6 is a magnetic head drive mechanism, and 40 is an actuator. Tossed horse mackerel unknown! Compensation for the Meguang world! Chikarasakuten 6 Aiming Diagram No.
Figure 3. Magnetic head training magnetic field (Oe) C, /N and 1/I-'' change to magnetic field Mf system 8 showing T
Fig. 4 Fig. 25 Conventional override method 2) Σ Nail diagram of the conventional override method 7 yen 5 t
figure

Claims (1)

[Scope of Claims] A magneto-optical recording medium (3) provided to be rotatable at high speed, and a required laser spot whose position is adjusted on the magneto-optical recording medium (3) and arranged so as to continuously irradiate the same. an optical head (4) which is driven for focus adjustment by an actuator (40); and an optical head (4) with the magneto-optical recording medium (3) in between.
a modulating magnetic field magnetic head (5) facing the magneto-optical recording medium (3) and disposed close to the magneto-optical recording medium (3); and a compensation magnetic field application disposed so as to compensate for leakage magnetic field from the actuator (40). means (1); and the compensation magnetic field applying means (
Compensation magnetic field adjusting means (2) for adjusting the magnetic field caused by (1)
).