JPH0418379B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to the recording of information on a disk-shaped magneto-optical medium.
The present invention relates to a magneto-optical recording and reproducing device that performs reproduction and erasing.

Conventional technology In recent years, there have been remarkable technological innovations in the capacity increase and high-speed access of optical disk recording and reproducing devices.
In particular, since magneto-optical media can be recorded, reproduced, and erased, their use in optical disks has been considered important. Magneto-optical media is a device that applies a perpendicular magnetic field to the medium and irradiates it with a finely focused laser beam to erase records using a thermomagnetic effect.A device that applies a magnetic field,
That is, emphasis has been placed on magnetic bias applying devices.

A conventional magneto-optical recording/reproducing device will be described below with reference to the drawings.

FIG. 6 shows a configuration diagram of a conventional magneto-optical reproducing device, and FIG. 7 is a sectional view of FIG. 6. In FIG. 7, 11 is a recording medium, 24 is a
This is a magnetic circuit for applying a perpendicular magnetic field to the recording medium 11 for recording and erasing information. magnetic circuit 2
4 is disposed at a position facing the optical head 12 with the recording medium 11 in between, and is a bar-shaped bar-shaped bar having a length equivalent to covering the scanning area of the optical head 12 along the access direction A of the optical head 12. A center yoke 25, an excitation coil 26 wound around the center yoke 25, and the center yoke 25.
A channel-shaped outer yoke 27 sandwiching the
It is composed of. The leading end 25a of the center yoke 25 facing the recording medium 11 is formed into a wedge shape, and the leading end surface of the center yoke 25 and the leading end surface of the outer yoke facing the medium are on the same horizontal plane, and are opposed parallel to the recording medium 11 with a distance S apart. ing.

The operation of the magneto-optical recording and reproducing apparatus configured as described above will be explained below. When the excitation coil 26 is energized, zero magnetic flux flows through the magnetic path consisting of the center yoke 25 and the outer yoke 27 as shown in FIG. 7, and the zero magnetic flux cuts the recording medium 11 as shown. If the distance S between the center yoke 25 and the recording medium 11 is made sufficiently small, a magnetic field in the perpendicular direction can be applied to the recording medium 11 corresponding to the tip of the center yoke 25. In addition, the magnetic field strength at this time is
By forming a into a wedge shape, the size can be increased, and by providing the external yoke 27, the excitation current can be reduced. (For example, Japanese Unexamined Patent Publication No. 59-119507) Problems to be Solved by the Invention However, the above configuration works well when the distance between the center yoke and the medium is small; When using a disc or a double-sided disc made by laminating two discs, it is necessary to increase the distance between the center yoke and the medium, which poses the problem of making it difficult to obtain a perpendicular magnetic field and reducing efficiency. Was.

If the perpendicularity of the magnetic field is poor, a tilted magnetic field will act on the recording medium, which will adversely affect recording and erasing characteristics. If the efficiency deteriorates, an excessive current must be passed through the excitation coil, which causes problems such as heat generation in the magnetic bias applying device and a large-capacity power supply, and also makes it difficult to miniaturize as a recording/reproducing device. had.

In view of the above-mentioned problems, the present invention provides a magneto-optical recording and reproducing device that can provide a highly perpendicular magnetic field even when the distance between the magnetic bias yoke and the recording medium is separated, and furthermore, the magnetic field changes less due to changes in distance. It provides:

Means for Solving the Problems In order to solve the above problems, the magneto-optical recording and reproducing apparatus of the present invention includes a center yoke having a length that covers the running range of the optical head by sandwiching the magneto-optical recording medium, and the center yoke. An excitation coil is wound around the center yoke, and an outer yoke is arranged to surround the excitation coil up to a point close to the tip of the center yoke.

Effect With this configuration, when current is passed through the excitation coil,
Since the distance between the center yoke and the outer yoke is small, the magnetic flux coming out of the center yoke has a small magnetic resistance, and the total magnetic flux increases. At this time, the horizontal component is much larger, but in terms of absolute numbers, the vertical component increases compared to the conventional shape, making the magnetic field stronger. However, at this time, since the vertical component of the magnetic flux changes greatly, the change in the magnetic field when the distance S between the recording medium and the center yoke changes is large. Therefore, by widening the width of the tip of the center yoke, Changes are smaller than those that do not increase in size.

Embodiment A magneto-optical recording and reproducing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a perspective view of a magneto-optical recording and reproducing apparatus in a first embodiment of the present invention.

In FIG. 1, 1 is a recording medium, and two disks are pasted together. 1a and 1b are the recording medium surfaces. When the disk is set as shown in FIG. 1, the recording medium surface 1a on the optical head side is the recording surface, and the recording medium surface 1b is the recording surface when the disk is inserted upside down. . Reference numeral 2 denotes an optical head, in which laser light irradiated from an objective lens 3 is focused on the recording medium surface 1a, and recording, reproduction, and erasing are performed. Also, the optical head 2 is accessed at high speed in the direction of arrow A. Reference numeral 4 denotes a magnetic circuit for recording and erasing information on the recording medium 1. The magnetic circuit 4 is placed at a position facing the optical head 2 while sandwiching the recording medium 1, and has a center long enough to cover the access area of the optical head 2. It consists of an outer yoke 7 disposed close to the tip of the center yoke 5 so as to surround the yoke 5 and the excitation coil 6 wound around the center yoke 5. The tip end 5a of the center yoke 5 facing the recording medium 1 has a wide cross section that is approximately in the shape of an inverted T. However, although not shown, the center yoke may have a cross section with a constant width. Further, the center yoke 5 and the outer yoke 7 are opposed to the recording medium 1 in parallel with a distance S apart.

The operation of the magneto-optical recording and reproducing apparatus configured as described above will be explained below with reference to FIGS. 1 and 2.

When a current is applied to the excitation coil 6, the excitation coil 6 winds around the center yoke 5 and the outer yoke 7 and closes to the tip of the center yoke 5 by, for example, 0.5 to 3 mm, as shown in FIG.
The magnetic flux emitted from the center yoke 5 has a smaller magnetic resistance than the conventional example due to the small distance between the center yoke 5 and the outer yoke, increasing the total magnetic flux. . At this time, the horizontal component is much larger, but the vertical component also increases, making the magnetic field stronger.

Figure 3 shows the results of simulating them using an actual computer. Curve Z is the result of analysis in the conventional example, curve X is the result of analysis in this embodiment, and curve Y is the result of analysis in which the cross section of center yoke 5 has a constant width in this embodiment.

The horizontal axis is the vertical position from the center yoke.
The vertical axis is the strength of the vertical magnetic field. Even if it is analyzed quantitatively as in the qualitative theory, if the outer yoke 7 is arranged so as to surround the excitation coil 6 up to a point close to the tip of the center yoke 5, the distance between the center yoke 5 and the outer yoke 7 will be Since it is smaller than the conventional one, the magnetic resistance is reduced, and the magnetic field strength of the vertical component is increased by about 60% at the same power. but,
When the cross section of the center yoke shown by the curve Y in FIG. 3 has a constant width, the magnetic field changes greatly when the distance S changes due to surface runout or the like.

By widening the width of the tip of the center yoke 5, it becomes a curve X, which is 15% wider than the one without widening.
This reduces changes in the magnetic field to a certain extent. Than these things. Even if the distance changes due to surface wobbling, etc., a strong vertical magnetic field can be stably applied. In addition, in this simulation, the shape was determined under the conditions that the recording medium was installed at a distance of 2.8 mm from the tip of the yoke.

As described above, according to this embodiment, the cross-sectional shape of the center yoke is approximately inverted T-shaped, and the tip of the outer yoke is placed close to the center yoke, so that the magnetic flux is concentrated, even at a place far away from the yoke. A strong vertical magnetic field is stably applied. Therefore, the magneto-optical recording and reproducing apparatus of the present invention can be used even in cases where the distance between the magnetic bias and the recording medium must be increased, such as in the case of a double-sided disc made by laminating two discs together or a disc with large surface wobbling. In addition, since the magnetic flux is concentrated, efficiency is improved, and the current flowing through the exciting coil,
It is possible to realize a magneto-optical recording and reproducing device that generates less heat and has less power supply capacity, and can achieve a number of excellent effects such as miniaturization of the device.

FIG. 4 is a perspective view of a magneto-optical recording/reproducing apparatus according to a second embodiment of the present invention, and FIG. 5 is a sectional view of a main part thereof.

In FIGS. 4 and 5, 1 is a recording medium, 2 is an optical head, and 3 is an objective lens. Reference numeral 14 denotes a magnetic circuit for recording and erasing information on the recording medium 1, which is disposed at a position facing the optical head 2 while sandwiching the recording medium 1, and the optical head 2 is accessed at high speed in the direction of arrow A by another means. Due to the angle 8, the magnetic circuit 14 is always movable together with the optical head 2, and is brought close to the tip of the center yoke 15 so as to surround the center yoke 15 that applies a magnetic field to one point and the excitation coil 16 wound around the center yoke 15. It consists of an outer yoke 17 arranged up to the point.

The tip end 15a of the center yoke 15 facing the recording medium 1 has an approximately inverted T-shaped cross section and is wider than the other parts. Further, the center yoke 15 and the outer yoke 17 are opposed in parallel to the recording medium with a distance S between them.

The operation of the magneto-optical recording and reproducing apparatus configured as described above is exactly the same as that of the first embodiment of the present invention.
The magnetic flux is concentrated and a strong vertical magnetic field is stably applied even at a distance from the yoke, improving efficiency and reducing the current flowing through the exciting coil, the amount of heat generated,
The power supply capacity is small, and the device can be made smaller.

Effects of the Invention The present invention provides a recording medium that is located opposite to the optical head with the magneto-optical recording medium in between, has a length that covers the running range of the optical head, and has a diameter that provides a magnetic field to one point while interlocking with the optical head. A center yoke whose tip portion has a wider width in a cross section of the tip facing the medium, an excitation coil wound around the selector yoke, and a center yoke arranged so as to surround the excitation coil up to a point close to the tip of the center yoke. By providing the outer yoke, the magnetic flux concentrates near the center of the tip of the center yoke, making it possible to form a magnetic field with many vertical components on the recording medium.
Even if the distance between the center yoke and the recording medium is large, the perpendicularity of the magnetic field can be maintained well, reducing the current flowing through the excitation coil, suppressing the heat generation of the magnetic bias applying device, and further downsizing the magneto-optical recording and reproducing device. can do.

Further, by widening the width of the tip on the cross section of the tip facing recording/reproducing, it is possible to suppress fluctuations in the magnetic field even when the distance between the recording medium and the magnetic bias yoke changes. Therefore, it is possible to apply a magnetic field of uniform strength over the entire scanning range of the optical head on the recording medium, and it is possible to stably record and erase information. It is possible to realize many excellent magneto-optical recording and reproducing devices, such as further miniaturization of magnetic recording and reproducing devices.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magneto-optical recording and reproducing apparatus according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIG. 3 is a diagram showing the distance between the recording medium and the tip of the center yoke. FIG. 4 is a perspective view of a magneto-optical recording and reproducing apparatus according to the second embodiment of the present invention, and FIG. 5 is an enlarged sectional view of the main part of FIG. FIG. 6 is a perspective view of a conventional magneto-optical recording and reproducing apparatus, and FIG. 7 is an enlarged sectional view of the main part of FIG. 6. 1... Recording medium, 2... Optical head, 3... Objective lens, 4, 14... Magnetic circuit, 5, 15...
Center yoke, 6, 16...excitation coil, 7,
17...outer yoke, 8...angle.

Claims (1)

[Scope of Claims] 1. A magneto-optical recording medium is sandwiched therebetween, and the width of the tip portion close to the recording medium is parallel to the recording medium and has a length that covers the running range of the optical head. a center yoke which is expanded in a direction such that its cross-sectional shape is approximately an inverted T-shape; an excitation coil wound around the center yoke; A magneto-optical recording/reproducing device comprising: an outer yoke; 2. The width of the tip, which is located opposite the optical head with the magneto-optical recording medium in between, is axially symmetrical and close to the recording medium and is close to the part where the optical spot of the optical head hits, in the direction horizontal to the surface of the recording medium. a center yoke whose cross section is approximately inverted T-shaped; an excitation coil wound around the center yoke; and an outer yoke arranged to surround the excitation coil up to a point close to the tip of the center yoke. A magneto-optical recording and reproducing device comprising: a center yoke and an outer yoke configured to be movable together with the optical head.