JPH02235202A - Bias magnetic field generator - Google Patents

Abstract

PURPOSE:To eliminate the need for the control of relative positioning between an optical head and a bias magnetic field generator in accurate tracking by narrowing the distribution of a main magnetic field component in the track direction of a recording medium and expanding the distribution in the tracking control direction rectangular to the track direction. CONSTITUTION:A conductor pattern 8 is formed on a magnetic body block 1, an insulating layer 7 is laminated so that nodes 5, 6 on both the ends of the pattern 8 are left and a spiral printed coil 2, a terminal 3 connected to an outer end and a terminal 4 connected to the pattern 8 at the node 6 are respectively formed on the surface of the layer 7 by means of conductor patterns. The coil 2 is formed as an elliptic vortex whose major axis is the y direction (the information track direction of a recording medium) and minor axis is the x direction (the tracking control direction rectangular to the tracks). Consequently, the bias magnetic field generator can be compacted by narrowing the distribution of the magnetic field component in the track direction of the recording medium, and in the case of accurate tracking control of the optical head, the correction of the positional shear of the bias magnetic field generator from the optical head can be made unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bias magnetic field generating device for applying a bias magnetic field to a recording layer of a magneto-optical recording medium in a magneto-optical recording method.

(Prior Art) A bias magnetic field generator conventionally used in a magneto-optical recording system is constructed as shown in FIG. 5K. Here, the bias magnetic field generator 52 and the optical head 5l are arranged so as to generate a generally uniform bias magnetic field over the entire information recording area 54 operated under torque control. It is arranged to sandwich the disk 5o. A current is supplied to the coil of the bias magnetic field generator 52 from a bias magnetic field generating power source 53, and the magneto-optical disk 50 is rotationally driven by a spindle motor 55.

In such a configuration, since a bias magnetic field must be generated corresponding to the entire information recording area 54K, it is difficult to avoid increasing the size and weight of the bias magnetic field generator and its power source. Furthermore, since it is difficult to apply a uniform bias magnetic field over the entire information recording area 54, the size and shape of recording bits formed on the magneto-optical disk K during recording become non-uniform, which can cause reading errors. Become. Furthermore, the power consumption for generating the bias magnetic field is large, and the magneto-optical disk 52 is affected by the temperature rise of the bias magnetic field generator 52.
As the temperature increases, the recording conditions during recording change, causing errors.

Therefore, a bias magnetic field generator has been proposed in which the bias magnetic field is applied to the magneto-optical disk by means of the optical head K, limited to the area where magneto-optical recording is actually being performed. This is as shown in FIG. 6K, in which a bias magnetic field generator 62 is connected via a support member 66 to an optical head 61 placed on the opposite side of the magneto-optical disk 60. ing. and a light beam 67 for recording and reproducing information on the optical head 61;
The bias magnetic field generator 62 and the optical head 61 are positioned relative to each other so that the center lines of the bias magnetic field generated by the bias magnetic field generator 62 generally coincide with each other. Therefore, when the optical head 61 is moved largely within the information recording area 64 by tracking control, the bias magnetic field generator 62 can follow this movement.

In addition, in the magneto-optical recording method of this raft, for example, a spring material with required spring characteristics is used for the part A of the support member 66 that connects the bias magnetic field generator 62 and the optical head 61, and The bias magnetic field generator 62 is configured to float above the surface of the magneto-optical disk 60 with a small gap by utilizing the airflow generated on the surface by the rotation of the disk 60.

With this configuration, the. The bias magnetic field generator as shown in FIG. 6 has problems with the bias magnetic field generator that applies a bias magnetic field over the entire moving region K as shown in FIG. It is possible to eliminate the disadvantage of power consumption and also eliminate the cause of error occurrence.

(Problems to be Solved by the Invention) However, even in the noise generator shown in FIG. 6, the following problems remain.

That is, in the bias magnetic field generator described above, since the uniform region of the generated bias magnetic field is narrow, it is necessary to precisely align the light flux 67 from the optical head 6l with the center line of the bias magnetic field generated by the bias magnetic field generator 62. However, for this reason, K requires highly accurate design and manufacturing, and requires highly accurate positioning, resulting in high cost.

Further, when the movement of the optical head is greatly controlled by the tracking control κ, the bias generator K is the support member 6.
However, in the process of scanning the optical beam, the deflection of the optical beam 67 due to the movement K of the optical head 61 and the vibration K of the actuator, and the deflection of the optical beam 67 due to the vibration K of the actuator are caused.
Correction control is required for the positional deviation K between the center line of the bias magnetic field and the light beam 67 due to the vibration K of 2. and <K, when the optical beam 67 is tracked by the precision tracking control actuator in the optical head 61,
Correction control for this positional deviation of the bias generator 62 is essential.

In addition, in the bias magnetic field generator shown in Fig. 6, since the coil is wound into a cylindrical shape, a considerable number of turns is required to generate the required magnetic field. The distance is very close, making it difficult to concentrate the magnetic field. Therefore, if the magnetic pole is made larger in order to widen the area of uniformity of the necessary magnetic field, the increase in inductance makes υ high-frequency drive difficult.

(Objective of the Invention) The present invention has been made based on the above circumstances, and it is possible to reduce the size of the bias magnetic field generator by narrowing the distribution of the main magnetic field component in the track direction of the recording medium, and to achieve a high transfer rate. In addition to enabling high-density recording, a uniform area of the bias magnetic field is secured in the range where the optical head is precisely tracked (in a direction perpendicular to the above-mentioned track direction), and the relative position with respect to the optical hollow is corrected. It is an object of the present invention to provide a bias magnetic field generator configured such that the bias field generator is not required.

(Means for Solving the Problem) Therefore, in the present invention, the direction K of the magnetic domain having the magnetization orientation is
Therefore, in a magneto-optical recording method in which the temperature of a magneto-optical recording medium is raised by a light beam from an optical head and a bias magnetic field is applied to represent information, the main magnetic field component is the recording medium of the recording medium. The magnetic field generating coil is arranged perpendicular to the layer, and its main magnetic field distribution is narrow in the direction of the information track of the magneto-optical recording medium to be recorded, and the direction of the magnetic domain whose temperature is increased by the light. The K is strong enough to reverse the above-mentioned track direction, and the direction K of the tracking control perpendicular to the direction of the track is wide, and the size is large enough to include the movable range of the light beam due to the precise tracking K of the optical head. .

(Function) In this configuration, the distribution of the main magnetic field component is narrowed in the track direction of the recording medium, so the bias magnetic field generator can be sufficiently miniaturized and weighed, resulting in high transfer rates and high performance. Enables density recording. In addition, when performing precise tracking control of the optical head, the light beam from the optical head moves within the necessary and sufficient uniform magnetic field area of the bias magnetic field generator, so there is no need to correct positional deviation of the bias magnetic field generator with respect to the optical head. However, there are several advantages in terms of construction and operation.

By making the magnetic field generating coil spiral, it is possible to secure the necessary and sufficient bias magnetic field size without increasing inductance, so the bias magnetic field generator can be made smaller, and the floating type can do.

(Embodiments) Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In this embodiment, the entire structure of the magneto-optical recording device is similar to that of the prior art example (see FIG. 6), so only the structure of the bias magnetic field generator according to the invention will be illustrated. As shown in FIGS. 1(-) and 1(b), in the first embodiment of the present invention, a conductor/arm turn 8 is formed on a magnetic block 1, and connection points 5. 6, an insulating layer 7 is laminated on the insulating layer 7, a spiral printed coil 2, a terminal 3 coupled to the outer end of the printed coil 2, and a terminal coupled to the conductive pattern 8 at the connection point 6. 4 are each formed by a conductive pattern. Note that the inner end of the printed coil 2 is connected to the connection point 5. Note that, if necessary, the insulating layer 7 may be applied to cover the printed coil 2.
A protective insulating layer may be laminated thereon.

Here, it is preferable to use a magnetic material having good high frequency characteristics, for example, high frequency ferrite, for the magnetic material block l. As for its magnetic characteristics, it is preferable to use a material with low loss at high frequencies and high magnetic permeability. In addition, in this embodiment K, the conductor/
In order to construct the printed conductors constituting the armature/8, glint coil 2, etc., it is preferable to employ a vapor deposition or suction method. Further, it is preferable to use a highly conductive material such as copper as the material. Here, methods such as etching techniques are also used to leave the desired pattern.

Here, the grid coil 2 is formed into an elliptical spiral whose long axis is in the y direction (the direction of the information track of the recording medium) and the short axis is in the x direction (the tracking control direction perpendicular to the above track). has been done. Therefore, the mounting direction of this bias magnetic field generator is similar to that of the magneto-optical recording device.
Must be adjusted to the recording medium.

Note that the bias magnetic field generator K configured as shown in FIG.
If a current flows from the terminal 3 to the terminal 4K, a +2 direction K magnetic field is generated, and conversely, if a current flows from the terminal 4 to the terminal 3K, a magnetic field is generated in the -z direction.

The distribution of the bias magnetic field generated by the bias magnetic field generator is as shown in FIG. Here, the horizontal axis K indicates the distance from the center of the glint coil, and the vertical axis K indicates the magnitude of the perpendicular magnetic field component applied to the recording layer K of the magneto-optical disk as the magneto-optical recording medium at that point K. . Curve A shows the distribution in the X direction in FIG. 1, and curve B shows the distribution in the y direction. Further, a straight line C indicates the minimum value of the bias magnetic field necessary for recording. Therefore, in the X direction, in other words, in the direction in which tracking control of the optical head is performed, alignment adjustment errors between the optical head and the bias magnetic field generator,
The magnetic field within the range of distance (for example, ±200 mm) including the movement range of the light beam by the tracking actuator is 2.
This means that it must be multiplied by 000e or more. In addition, regarding the direction K perpendicular to the moving direction of the tracking actuator, the alignment vI of the center line of the optical head's light beam and the bias magnetic generator in the y direction K
4! It is sufficient that it is 20,000 or more within a range (for example, ±100 μm) that can cover I errors, vibrations, and positional deviations including changes over time. As described above, the range of the main component of the magnetic field that must be applied to the recording layer K of the magneto-optical recording medium is greatly different between the tracking direction of the optical head and the direction perpendicular to this. As for the tracking direction, it is sufficient that the uniform area of the magnetic field (in the X direction) covers the range in which the optical beam from the optical head moves due to precision tracking.

Thus, the configuration K of the bias magnetic field generator according to the present invention K
According to the invention, a precision tracking actuator generates a uniform magnetic field in a sufficiently wide area in the direction of movement of the light beam, and also generates a large magnetic field in an unnecessary wide area in the direction of the information track perpendicular to this. Therefore, fluctuations in recording pits due to non-uniformity K of the magnetic field are small, and the frequency of errors can be significantly reduced. Furthermore, since a large magnetic field is not applied to areas where no recording is being performed, the reliability of information can be ensured over a long period of time without changing the recorded information K. In particular, the length of the magnetic block can be made as short as possible in the y-direction, which is advantageous in making the bias magnetic field generator smaller and lighter.

Further, since the coil spacing can be narrowed in the y direction, the inductance of the coil 2 can be reduced, and the high frequency switching characteristics can be improved.

FIG. 3K shows another embodiment of the invention. Note that the upper glint coil 3l is shown in a plan view here. The shape of the coil 31 is a rectangular spiral with a long K dimension in the X direction. In addition, the code|symbol 32 is a magnetic material block here, 33.34 is a terminal, 35. 36 is a connection point.

FIGS. 4(a) and 4(b) show a further embodiment of the invention. Here, the upper printed coil 4l is similar to the embodiment shown in FIG. A coil 46 is configured to connect each connection point 44 . 45 are connected to each other to ensure twice the number of coil turns. Therefore, it is possible to generate twice as much magnetic field with the same drive current. This is effective when for some reason it is not possible to bring the bias magnetic field generator and the magneto-optical disk closer together, or when a large bias magnetic field is required.

Of course, the shape of the spiral can be modified into a rectangle as shown in Figure 3 or other oval shapes. (Effects of the Invention) The present invention has been described in detail above, and in the track direction of the recording medium, the distribution of the main magnetic field component is narrowed and the strength is necessary and sufficient to reverse the direction of the magnetic domain whose temperature is increased by light. In addition, the optical head is wide in the direction of tracking control that is orthogonal to the tracking direction, and is sized to include the movable range of the light beam due to the precision tracking K of the optical head. There is no need to control the relative positioning between the magnetic field generator and the bias magnetic field generator, which is advantageous in terms of structure and control.

As a result, costs can be reduced and errors occurring during recording can be reduced. In addition, since the magnetic field is not applied to an extra range during recording, there is no risk of changing the recorded information, ensuring long-term reliability of information, and because K can be shortened as much as possible in the track direction. k. Since the bias magnetic field generator is miniaturized, effects such as the ability to hold the magnetic head in a floating manner can be obtained. In this way, high-speed movement of the optical head such as seeking is ensured, vibrations are reduced, and further stability and high reliability can be obtained.

[Brief explanation of the drawing]

Figures 1 (&) and (b) are a top view and a sectional view showing an embodiment of the present invention, Figure 2 is a magnetic field distribution diagram for a bias magnetic field generator according to the present invention, and Figure 3 is a diagram of the magnetic field distribution according to the present invention. A top view of another embodiment of FIG. 4(.). (b) is a top view of yet another embodiment, a partially removed top view, and FIGS. 5 and 6 are schematic diagrams of a magnetic recording device showing the configuration of a conventional bias magnetic field generator, respectively. 1... Magnetic block, 2... Glint coil, 3
．． 4...terminal, 5.6...connection point, 7...insulating layer, 8...conductor pattern/. Agent Patent Attorney Seki Yamashita

Claims (1)

[Claims] In a magneto-optical recording method in which the temperature of a magneto-optical recording medium is raised by a light beam from an optical head and a bias magnetic field is applied so that information is expressed by the direction of magnetic domains having magnetization orientation, the main magnetic field component is The magnetic field generating coil, which is arranged perpendicular to the recording layer of the recording medium, has a main magnetic field whose distribution is narrow in the direction of the information track of the magneto-optical recording medium on which recording is performed, and whose temperature is increased by the light. It has sufficient strength to reverse the direction of the magnetic domain, and is wide in the tracking control direction perpendicular to the track direction, and has a size that includes the range of movement of the light beam due to precision tracking of the optical head. A bias magnetic field generator characterized by: