JPS62185269A - Photomagnetic recorder - Google Patents

Abstract

PURPOSE:To supply magnetic field at all time with a constant intensity to a photomagnetic recording medium by so controlling that an optical head part and an external magnetic field generating part are positioned at a prescribed position against a photomagnetic recording medium, and make the external magnetic field generating part smaller in size and consume less power. CONSTITUTION:The optical head part 5 and the external magnetic field generating part 10 are provided facing each other with the photomagnetic recording medium between themselves. Also a focusing error detecting circuit 11 and a tracking error detecting circuit 12 which are to detect the position of the part 5 in relation to the photomagnetic recording medium. By using the resulting detection signals, an objective lens plane 23a and a solenoid plane 13a are controlled so that at all time they face each other with a constant distance between themselves. In such a way, an electromagnetic coil 13 can be made able to supply a magnetic field with a constant intensity to a laser light projection plane made of a vertically magnetized film, and also the photomagnetic recording device itself can be made smaller in size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording device that uses a magneto-optical recording medium having a perpendicular magnetization film, such as a magneto-optical disk, as a recording medium.

[Summary of the invention]

The present invention provides a magneto-optical recording device using a magneto-optical recording medium having a perpendicular magnetization film such as a magneto-optical disk as a recording medium, in which an optical head section and an external magnetic field generating section are provided so as to face each other with the magneto-optical recording medium in between. A position detection section is also provided to detect the position of the optical head section relative to the magneto-optical recording medium, and a position detection signal obtained from the position detection section is used to position the optical head section and the external magnetic field generating section at a predetermined position relative to the magneto-optical recording medium. By controlling the external magnetic field to a small size and with low power, it is possible to always apply a magnetic field of constant strength to the magneto-optical recording medium, and it is also compatible with magnetic field modulation methods. be.

[Conventional technology]

Generally, recording on a magneto-optical disk is performed by irradiating the perpendicularly magnetized film of the magneto-optical disk with a laser beam to locally raise the temperature, and at the same time applying an external magnetic field to orient the magnetization of the local area in the direction of the magnetic field. ing. That is, before recording, as shown in FIG. 3A, the perpendicularly magnetized film (1) formed on glass, acrylic, etc. (not shown) forming the substrate of the magneto-optical disk is perpendicular to the film surface. This perpendicularly magnetized film (11
As shown in FIG. 3B, a predetermined magnetic field that does not reverse the magnetization in the recording direction, the so-called recording bias magnetic field Hw, is applied, and a spot of laser light LB is irradiated as shown in FIG. 3C, and this spot area is a cylindrical magnetic domain whose magnetization is reversed at
Information is recorded by forming a so-called magnetic bubble. On the other hand, when rewriting information on the perpendicularly magnetized film (11) recorded in this way,
When erasing the magnetic bubble (2) of the perpendicularly magnetized film (1) shown in the figure, the perpendicularly magnetized film (1) is removed as shown in Fig. 3.
While applying an erasing magnetic field HE in the same direction as the magnetization direction in the unrecorded state, a laser beam LB is applied to the
irradiation to create a magnetic bubble with reversed magnetization direction (
The magnetization direction of 2) is returned to the forward direction to create a magnetic bubble (2).
) is deleted.

In this way, when recording and erasing information on a magneto-optical disk, it is necessary to apply external magnetic fields H- and HE whose directions of magnetic fields are opposite to each other, and the recording bias magnetic field Hw is, for example, about 3000 e to 5 GOOe. For example, a magnetic field of about 10,000 e is considered optimal as an erase bias magnetic field. Here, the use of permanent magnets or electromagnets can be considered as a means for obtaining these recording bias magnetic field Hi4 and erasing bias magnetic field Ig, but the main part of a magneto-optical recording device using permanent magnets is shown in Fig. 4. Various things have been proposed.

In FIG. 4, (3) indicates a magneto-optical disk, and this magneto-optical disk (3) is constructed by depositing a perpendicularly magnetized film (1) on a glass substrate (4), which is a non-magnetic substrate. , and rotate around the central axis 0-O'. In addition, (5) shows an optical head section that performs optical recording and reproduction by irradiating the perpendicular magnetization film (11) of the magneto-optical disk (3) with a laser beam LB, and this optical head section (5) is indicated by arrow A. (6) moves in the radial direction of the magneto-optical disk (3).
), and this permanent magnet (6) is magnetized with one side as N pole and the other side as S pole, and the rotating shaft ( 7a) and (7b), and in the case of recording, as shown in FIG. 5, the magneto-optical disk (3) is placed with its north pole facing the magnetic disk (3), and a forward magnetic field is applied to the perpendicularly magnetized film (1). Recording bias magnetic field Hw
In addition, in the case of erasing, as shown in FIG. 6, it is possible to place the S pole side facing the magneto-optical disk (3) and apply a magnetic field in the opposite direction to the perpendicularly magnetized film (1), that is, an erase bias magnetic field HI: It is being done as much as possible. In this case, the rotating shaft (7a
) (7b) is provided eccentrically to the N-pole side, and the N-pole surface is opposed to the magneto-optical disk (3), and the distance dw between the N-pole surface and the magneto-optical disk (3) and the S-pole surface are Magneto-optical disk (3
), so that the distance dE between the S pole surface and the magneto-optical disk (3) is dw>dB, and the perpendicularly magnetized film (
The erasing bias magnetic field HE applied to 1) is made larger than the recording bias magnetic field Hw. Further, the N pole and the S pole are uniform magnetic fields H- and S-pole, respectively, on the irradiation part of the laser beam LB over the entire scanning width of the laser beam LB by the optical head part (5) along the radial direction of the magneto-optical disk (3). It is arranged to extend along the radial direction of the magneto-optical disk (3) so as to be able to provide HI:. Also, the rotating shaft (7a)
The permanent magnet (
6) and the optical head section (5) can perform recording and erasing together.

However, in such a magneto-optical recording device, it is necessary to arrange the permanent magnets (6) at extra intervals in consideration of the warping of the magneto-optical disk (3), and for this reason, the permanent magnets (6) that are strongly magnetized must be arranged at an extra interval. There was an inconvenience that (6) was required. In addition, uniform magnetic fields Hw and HE are applied to the laser beam irradiation area.
A permanent magnet (6) is attached to a magneto-optical disk (3) to provide
Since it is necessary to extend the magnetic field along the radial direction of the permanent magnet (6) and to provide a rotation drive section for the permanent magnet (6), there are disadvantages in that the utilization efficiency of the magnetic field is very poor and the device becomes large in size6. Furthermore, if a magnetic field modulation method is used to perform so-called overwriting, the permanent magnet (6) must be reversed at high speed, and the magneto-optical recording device shown in the example in Figure 4 is not suitable for this purpose. There was an inconvenience.

In this case, instead of the permanent magnet (6), it may be possible to provide an electromagnet (electromagnetic coil) that extends in the radial direction of the magneto-optical disk (3) in the same way as the permanent magnet (6). As in the case of magnet (6), there are disadvantages such as poor magnetic field utilization efficiency and an increase in the size of the device, and since this electromagnetic coil is large, the inductance of this electromagnetic coil is large, so the magnetic field modulation method is When a magnetic field is reversed at a high frequency to perform so-called overwriting, a large amount of power is required and the drive circuit for this becomes large-scale, which is disadvantageous.

Therefore, in recent years, a magneto-optical recording device, the main part of which is shown in FIG. 7, has been proposed.

This example in FIG. 7 shows the perpendicular magnetization film il of the magneto-optical disk (3).
The optical head part (5) provided on the l side is provided with a winding frame (8) having a through hole through which the laser beam LB can pass, and an electromagnetic coil (9) is wound around this winding frame (8). It is something.

This example in FIG. 7 has the advantage that the electromagnetic coil (9) can be made smaller.

[Problem that the invention seeks to solve]

However, in the magneto-optical recording device of the example shown in FIG. )
The force applied to the focusing and tracking actuator mechanism (not shown) provided in There was a problem in that the optical head section (5) also had to be enlarged.

In view of the above, it is an object of the present invention to provide a magneto-optical recording device that is small in size and has a low power consumption, can always apply a magnetic field of constant strength to a magneto-optical recording medium, and is also compatible with a magnetic field modulation method. purpose.

[Means for solving problems]

As shown in FIGS. 1 and 2, the magneto-optical recording device according to the present invention includes an optical head section (5) and an external magnetic field generating section (10) facing each other with a magneto-optical recording medium (3) in between. and a position detecting section (11) (12) for detecting the position of the optical head section (5) with respect to the magneto-optical recording medium (3). The signal causes the optical head section (5) and the external magnetic field generating section (10
) is controlled to a predetermined position with respect to the magneto-optical recording medium (3).

[Effect]

According to the present invention, the optical head section (5) and the external magnetic field generating section (10) are arranged so as to face each other with the magneto-optical recording medium (3) in between.
), the optical head section (5) does not become larger as in the example shown in FIG.

In addition, in this case, the magneto-optical recording medium (
position detection unit (11) that detects the position relative to (1)
2), and the optical head section (5) and the external magnetic field generating section (lO) are set at a predetermined position with respect to the magneto-optical recording medium (3) by the position detection signals obtained from the position detecting sections (11) and (12). Since the external magnetic field generator (
By downsizing the electromagnetic coil (13) constituting 10), it is possible to always apply a constant strength of external magnetic field H- or HE to the perpendicularly magnetized film (1) even if the external magnetic field generating section (10) is downsized. As a result, the magneto-optical recording device itself can be downsized.

Furthermore, as mentioned above, the electromagnetic coil (13) can be miniaturized and the inductance L of this electromagnetic coil (13) can be reduced, so this electromagnetic coil (13) can be driven with small electric power, and the magnetic field modulation method can be used. Even when overwriting is performed by employing the above method, the drive circuit required for this can be constructed on a small scale, and it can also be adapted to the magnetic field modulation method.

〔Example〕

Hereinafter, with reference to FIGS. 1 and 2, an embodiment of the magneto-optical recording apparatus of the present invention will be described in which the magneto-optical recording apparatus is applied to a magnetic field modulation method.

In FIGS. 1 and 2, parts corresponding to those in FIGS. 3 to 7 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, as shown in FIG. The rotational driving force of the motor (18) is transmitted to the guide screw member (16) via the first pulley (19), the belt (20), and the second pulley (21). ) to move the feed member (14) in the direction of arrow B, and as will be described later, the optical head section (5) attached to this feed member (14) and the electromagnetic field forming the external magnetic field generating section are rotated. The coil device section (10) and the magneto-optical disk (3)
be able to move in the radial direction.

That is, in this example, the lower side (14) of the feeding member (14)
An optical head portion (5) is provided at the end of the upper side of a). In this case, a well-known laser irradiation device (22) is installed in the optical head section (5), and the perpendicular magnetization film (11) of the magneto-optical disk (3) is irradiated with laser light LB to raise the temperature of the irradiated part. arrow C shown in FIG. 1 for focusing and tracking.
and an actuator mechanism (24) that moves in the direction of D.
.

In addition, a light receiving element (not shown) using, for example, a four-split element system is provided in this optical head section (5) to receive the reflected light from the perpendicularly magnetized film (t), and the signal obtained by this light receiving element is detected as a focus error. The focus error detection signal obtained by the focus error detection circuit (11) is supplied to the detection circuit (11) and sent to the focusing drive circuit (25).
and the focusing signal obtained by the focusing drive circuit (25) is sent to the actuator mechanism (25).
4) to enable focusing. Further, the signal obtained by the above-mentioned light receiving element is supplied to the tracking error detection circuit (12), the tracking error detection signal obtained by this tracking error detection circuit (12) is supplied to the tracking drive circuit (26), and the tracking error detection circuit (12) is supplied to the tracking drive circuit (26). The tracking signal obtained by the circuit (26) is supplied to the actuator mechanism (24) to enable tracking. Note that it is of course possible to obtain a reproduced signal from the signal obtained by the above-mentioned light receiving element.

Further, in this example, the upper side (14b) of the feeding member (14)
) is provided with an electromagnetic coil device section (10) constituting an external magnetic field generating section on the lower surface end portion, that is, the surface facing the optical head section (5). In this case, this electromagnetic coil device section (1
0) in the directions of arrows E and F shown in FIG. It shall be provided as follows. Then, the focus error detection signal obtained by the above-mentioned focus error detection circuit (11) is transferred to the polarity inversion circuit (2).
B) to the focus direction drive circuit (29), and the focus direction drive signal obtained by the focus direction drive circuit (29) is supplied to the actuator mechanism (27) to control the electromagnetic coil (13) during focusing. The movement is made to coincide with the movement of the objective lens (23), and the tracking error detection circuit (12)
) is supplied to the tracking direction drive circuit (30), and the tracking direction drive signal obtained by the tracking direction drive circuit (30) is supplied to the actuator mechanism (27), which controls the electromagnetic coil during tracking. The movement of (13) is made to coincide with the movement of the objective lens (23).

In this way, the optical head section (5) and the electromagnetic coil device section (10)
In this case, the objective lens surface (23a) and the electromagnetic coil surface (13a) are not only controlled so as to always face each other, but also the objective lens surface (23a) and the electromagnetic coil surface (13a)
) is also controlled so that it is always constant, and in this case,
The objective lens (23) is always focused on the perpendicularly magnetized film (1), and the objective lens surface (23
Since the distance between a) and the perpendicular magnetization film (1) is always kept constant, the distance between the electromagnetic coil surface (13a) and the perpendicular magnetization film +1) is also always kept constant, and the distance between the perpendicular magnetization film (1) The magnetic field Hw or HE can always be supplied at a constant strength.

Therefore, in this example, it is sufficient to provide a small diameter and small electromagnetic coil (13) without providing a large electromagnetic coil.
In this case, since the inductance of the electromagnetic coil (13) becomes small, a large magnetic field can be generated with a small current, making it possible to employ a magnetic field modulation method. Therefore, in this example, the information recording signal is transferred to the magnetic field modulation circuit (
31) to obtain a magnetic field modulation signal, this magnetic field modulation signal is supplied to the electromagnetic coil (13), and in combination with the laser beam LB supplied from the optical head section (5), the magneto-optical disk (3
) to enable recording based on an information recording signal on the perpendicularly magnetized film (1). The rest of the configuration is the same as that of the conventional example.

In the magneto-optical recording device of this example configured in this way,
Since the optical head section (5) and the electromagnetic coil device section (10) are provided so as to face each other with the magneto-optical disk (3) in between, the optical head section (5) as shown in the example in FIG. ) has the advantage of not becoming large.

Further, a focus error detection circuit (11) and a tracking error detection circuit (12) are provided, and the focus error detection signal and tracking error detection signal obtained by the focus error detection circuit (11) and the tracking error detection circuit (12) are used. and the objective lens surface (23
a) and the electromagnetic coil surface (13a) always face each other, and the objective lens surface (23a) and the electromagnetic coil surface (13a)
3a), so even if the electromagnetic coil (13) is made small and has a small diameter, the magnetic fields H- and HE of constant strength are always applied to the laser beam of the perpendicularly magnetized film (1). It has the advantage that it can be applied to the irradiated surface.

Furthermore, when the electromagnetic coil (13) is made smaller in diameter and smaller in this way, the inductance of the electromagnetic coil (13) becomes smaller, making it possible to generate a sufficient magnetic field with a small current, making it possible to There is the advantage that this electromagnetic coil (13) can be driven by a drive circuit and can be adapted to a magnetic field modulation method.

In the above embodiments, the magneto-optical recording device of the present invention is applied to a magnetic field modulation method, but instead, it can also be applied to an optical modulation method, and in this case, the same effects as described above can be obtained. Of course you can get it.

Furthermore, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and can take various other configurations without going over the gist of the present invention.

〔Effect of the invention〕

According to the present invention, since the optical head section and the external magnetic field generation section are provided so as to face each other with the magneto-optical recording medium in between, the optical head section becomes larger as shown in the example in FIG. There is a benefit of not having to do it.

In addition, since the optical head section and the external magnetic field generating section are controlled to a predetermined position with respect to the magneto-optical recording medium, by miniaturizing the electromagnetic coil, the external magnetic field generating section (10
) is advantageous in that an external magnetic field of constant strength can always be applied to the magneto-optical recording medium, and at the same time, the magneto-optical recording apparatus itself can be made smaller.

Furthermore, since the electromagnetic coil can be made smaller and the inductance of this electromagnetic coil can be reduced, it is possible to drive this electromagnetic coil with small electric power. There is an advantage that the required drive circuit can be constructed on a small scale and that it can also be adapted to magnetic field modulation methods.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a main part of an embodiment of the magneto-optical recording device of the invention, FIG. 2 is a configuration diagram showing a main part of an embodiment of the invention, and FIG. 3 is for explaining the invention. FIG. 4 is a diagram showing the main parts of an example of a conventional magneto-optical recording device, FIGS. 5 and 6 are diagrams for explaining the example in FIG. 4, and FIG. FIG. 3 is a configuration diagram showing the main parts of another example of a magneto-optical recording device. (1) is a perpendicular magnetization film, (3) is a magneto-optical disk, (5)
is the optical head section, (10) is the electromagnetic coil device section, (11)
(12) is a tracking error detection circuit, (13) is an electromagnetic coil, and (31) is a magnetic field modulation circuit.

Claims (1)

[Claims] An optical head section and an external magnetic field generation section are provided so as to face each other with a magneto-optical recording medium in between, and a position detection section is provided for detecting the position of the optical head section with respect to the magneto-optical recording medium, and the position detection section A magneto-optical recording device, characterized in that the optical head section and the external magnetic field generating section are controlled to a predetermined position with respect to the magneto-optical recording medium by the obtained position detection signal.