JPS59119507A - Photo-magnetic recorder - Google Patents

Abstract

PURPOSE:To obtain a compact and light-weight optical head and at the same time to improve the generating efficiency of magnetic field by providing a magnetic circuit for application of vertical magnetic field of a recording medium having the length covering the scan region of the optical head at a position opposite to the optical head and holding the recording medium. CONSTITUTION:A magnetic flux phi flows to a magnetic path consisting of a magnetic pole 5 and a yoke 7 when an exciting coil 6 is conducted electricity. This flux phi cuts a recording medium 1. When the distance S is reduced satisfactorily between the pole 5 and the medium 1, it is possible to impress a magnetic field having the direction vertical to the medium 1 which is opposite to the tip of the pole 5. In this case, the intensity of the magnetic field can be increased by the tip part 5a of the pole 5 into a wedge form. In addition, the excited current quantity is also reduced by providing a yoke 7. At the same time, the magnetic fields having approximately equal intensity can be obtained if an optical head 2 has an access to any position since the pole 5 has such length that can cover the access range of the head 2.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to an optical-magnetic recording device that performs thermomagnetic recording by applying a magnetic field to the recording medium and irradiating the medium surface with a laser beam, and particularly relates to This invention relates to the improvement of a magnetic field application mechanism for efficiently obtaining the magnetic field necessary for recording and erasing information.

(2) Background of the technology Magneto-optical recording devices such as magneto-optical disk devices perform thermomagnetic recording and erasing by applying a magnetic field to the recording medium and irradiating the medium surface with a laser beam. Writing and erasing the information requires applying a magnetic field perpendicular to the medium.

(3), Prior art and problems Conventionally, as for applying a magnetic field perpendicularly to a recording medium,
A solenoid coil is used, and this solenoid coil is arranged concentrically around an objective lens for condensing laser light onto a medium, and is integrated into a head including an optical system.

However, since the applied magnetic field required for recording and erasing this type of information is as large as 200 to 3,000 seconds, the number of turns of the tunneloid coil also increases by about nine. The problem with point B is that the so-called optical head, which includes the optical system such as the objective lens, becomes larger and heavier, and the inertia of the optical head becomes large, which interferes with the high-speed access system of the optical head. Since the coil is arranged concentrically around the lens, it is necessary to use an air-core coil, which makes it impossible to increase the efficiency of magnetic field generation.

(4) 0 Purpose of the Invention The present invention solves the above-mentioned conventional problems, and by separating the magnetic field application coil from the optical head, the optical head is made smaller and lighter, and at the same time, the magnetic field is generated. An object of the present invention is to provide a magneto-optical recording device that increases the sardine rate.

(5) 1 Structure of the Invention In order to achieve the above object, the magneto-optical recording device of the present invention comprises:
In a device that performs thermomagnetic recording by applying a magnetic field to a recording medium and irradiating the medium surface with a laser beam, an optical system that records and reproduces information by scanning the recording medium surface and irradiating the medium surface with a laser beam. A magnetic circuit for applying a perpendicular magnetic field to a medium having a length that sandwiches the recording medium and covers the scanning area of the optical head is disposed at a position facing the head.

(6) Example of 0 invention Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of a magneto-optical recording device according to the present invention, in which 1 is a recording medium, 2 is an optical head, and this optical head 2 is moved by a feeding device (not shown). 1, and has an objective lens 3 and a focusing mechanism (not shown) that controls the focus of the objective lens 3 to be on the surface of the recording medium 1. Furthermore, a laser light source (not shown) and an optical system for guiding the laser light to the objective lens 3 are built in, and while scanning the surface of the medium with the optical head 2 configured as described above, the laser light is passed through the entire objective lens 3. By irradiating the medium surface with laser light and accessing it in the direction of arrow A, information can be recorded and reproduced.

Reference numeral 4 denotes a magnetic circuit for applying a perpendicular magnetic field to the recording medium 1 for recording and erasing information, and this magnetic circuit 4 is disposed at a position facing the optical head 2 with the recording medium 1 in between. A bar-shaped magnetic pole 5 is provided, and has a length corresponding to enough to cover the access area of the optical head 2 along the access direction of the optical head 2, an excitation coil 6 wound around this magnetic pole 5, and the above magnetic pole. 5 and a channel-shaped yoke 7 surrounding the yoke 5. Further, the tip end 5a of the magnetic pole 5 facing the recording medium 1 is formed into a wedge shape, and the tip end surface and the medium facing end surface of the yoke 7 are on the same horizontal plane and are parallel to the recording medium 1 with a distance S apart. is facing.

In this embodiment with the above configuration, when the excitation coil 6 is energized, a magnetic flux φ flows through the magnetic path consisting of the magnetic pole 5 and the yoke 7 as shown in FIG. Cut into pieces. If the distance S between the magnetic pole 5 and the medium 1 is made sufficiently small, a magnetic field can be applied to the medium 1 facing the tip of the magnetic pole 5 in a direction perpendicular to this. Furthermore, the strength of the magnetic field at this time can be increased by forming the tip 5a of the magnetic pole 5 into a wedge shape, and by providing the yoke 7, the excitation current can also be reduced.

Furthermore, since the magnetic pole 5 has a length sufficient to cover the access range of the optical head 2, the strength is almost the same no matter which position the optical head 2 accesses in the direction of the arrow in FIG. A magnetic field can be obtained. It is thought that the magnetic field applied to the medium decreases slightly at the ends of the magnetic pole 5 in the longitudinal direction, but this can be avoided by making the length of the magnetic pole 5 sufficiently longer than the access range of the optical head 2.

As described above, according to this embodiment, since the magnetic circuit 4 that applies a perpendicular magnetic field to the recording medium is separated from the optical head, the optical head 2 can be made smaller and lighter, and high-speed access is possible. The magnetic circuit for applying a magnetic field can be configured in any manner regardless of the optical head, and the efficiency of magnetic field generation can be increased.

FIG. 3 shows another embodiment of the magnetic circuit for applying a vertical magnetic field according to the present invention. The difference from FIG. 1 is that the yoke 7 forming the magnetic path is angled, and the shape including the magnetic pole 5 is is shaped like a channel. In this embodiment, even if the shape of the yoke 7 is changed, the operating principle is the same as in the case of FIG. 1.

FIG. 4 shows an example in which the method of the present invention is applied to a single-plate magneto-optical disk device, where 10 is the device casing, 1
1 is a recording medium (disc) installed inside the casing 10
A rotary spindle 1 and a head drive motor 12 are also installed in the casing 10, and an optical hand 2 is attached to the tip of a linear shaft 13 of the head drive motor 12. Further, a magnetic circuit 4 for applying a perpendicular magnetic field to the recording medium 1 is installed on the inner wall of a device lid 14 that is openably and closably attached to the casing 10, facing the optical head 2.

If such a method of attaching the magnetic circuit 4 is adopted, there will be no problem in attaching and detaching the recording medium 1.

Note that the magnetic circuit 4 in the present invention is not limited to that of the above embodiment, and for example, as described in detail above (8) 8 Effects of the Invention, the magnetic circuit 4 only includes the magnetic pole 5. According to the present invention, the vertical magnetic field can be applied to the medium. By separating the magnetic circuit for applying the magnetic field from the optical head, the optical head can be made smaller and lighter, and the optical head can be accessed at high speed. Therefore, the efficiency of magnetic field generation can be increased.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts showing an example of a magneto-optical recording device according to the present invention, FIG. 2 is an enlarged sectional view of a magnetic circuit for applying a magnetic field in the present invention, and FIG. 3 is a magnetic circuit for applying a magnetic field in the present invention. FIG. 4 is a perspective view showing another embodiment of the circuit, and is an explanatory diagram showing an example in which the method of the present invention is applied to a single-plate magneto-optical disk device. Explanation of the symbols 1 is a recording medium, 2 is an optical head, 3 is an objective lens, 4 is a magnetic circuit for applying a magnetic field, 5 is a magnetic pole, 6 is an excitation coil, and 7 is a yoke. Figure 1 Figure 2 41 Figure 3 Figure 4

Claims (1)

[Claims] In a device that performs thermomagnetic recording by applying a magnetic field to a recording medium and irradiating the medium surface with a laser beam, an optical head that records and reproduces information by irradiating the medium surface with a laser beam while scanning the recording medium surface. 1. A magneto-optical recording device, characterized in that a magnetic circuit for applying a perpendicular magnetic field to the medium is disposed at a position facing the recording medium and having a length to sandwich the recording medium and cover the scanning area of the optical head.