JPH0528407A - Bias magnetic field generator - Google Patents

Abstract

PURPOSE:To miniaturize a magneto-optical recorder to suppress the temperature rise of the inside of the device and to generate appropriate magnetic field strength by a magnetic field generating means. CONSTITUTION:The magnetic recording medium confronting means 41 of a magnetic field generator is extended in the direction of movement parallel to the magnetic recording medium face of an optical pickup and simultaneously formed longer than moving distance of the optical pickup. Further, a width size in the direction of intersecting orthogonaly with the extending direction of the magnetic recording medium confronting means 41 is formed so that the width size (t) in a non-connecting point is smaller than the width size S in a connecting point with a coil winding means 39. Although this is the small- sized magnetic field generating device, the magnetic field strength is enhanced efficiently over the recording area. Further, power consumption is small and the temperature rise of the inside of the device is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias magnetic field generator used in a magneto-optical recording apparatus for recording information by irradiating an optical beam while applying a magnetic field to a magnetic recording medium.

[0002]

2. Description of the Related Art A magnetic recording medium used in a magneto-optical recording apparatus has a magnetic film formed on the surface of the medium by a method such as vapor deposition. The magnetic film has magnetic anisotropy in a direction perpendicular to the film surface. Is pre-magnetized in one direction in the vertical direction. Then, when a light beam is applied to the magnetic recording medium while applying a reverse magnetic field, the direction of magnetization is reversed. Therefore, in order to record information, the direction of magnetization is reversed. Further, when the light beam is irradiated while applying the initial magnetization direction, the recorded information can be erased. In order to reproduce the recorded information, an optical beam is first irradiated onto the magnetic recording medium. Then, the reflected light from the magnetic recording medium receives the curling effect, and the plane of polarization of the light rotates relative to when it is incident on the magnetic recording medium. Information is reproduced by detecting the rotation direction of this rotation angle.

In order to record and erase information as described above, a bias magnetic field generator is used to apply a magnetic field to the surface of the magnetic recording medium. Various bias magnetic field generators have been proposed so far. For example, in Japanese Patent Laid-Open No. 2-50302, the main magnetic pole is made to face the entire recording area of the magnetic recording medium, and the main magnetic pole is further wound around the coil. And a recording medium facing portion, and the length of the coil wire is shortened to reduce the direct current resistance, heat generation and unnecessary current consumption are suppressed, and the magnetic field distribution is made uniform. Further, in Japanese Patent Laid-Open No. 2-12677, a magnetic bias means is fixed on a cartridge holder, and the magnetic bias means has a coil wound in a cylindrical yoke having a bottom, and the coil is wound. It is disclosed that a center yoke having a length corresponding to a recording area of a magnetic disk is fixed to an axial end of the center yoke so that the center yoke is made small and thin.

[0004]

However, as in the prior art example, the bias magnetic field generator is made small and thin, and the length of the coil wire is shortened to reduce the DC resistance, resulting in heat generation and unnecessary current consumption. If the number of turns of the coil is reduced in order to suppress the magnetic field and make the magnetic field distribution uniform, the following problems occur. That is, in order to secure a constant magnetic field strength on the surface of the recording medium, it is necessary to increase the current value. When the current value is increased, the power consumption increases and the amount of heat generation also increases. The increase in the amount of heat generation causes a temperature rise inside the magneto-optical recording device, which hinders the recording and reproduction of information.

The present invention has been proposed to solve the above-mentioned problems, and it is possible to obtain a proper magnetic field strength while reducing the size of the magneto-optical recording apparatus and suppressing the temperature rise inside the magneto-optical recording apparatus. It is an object of the present invention to provide a bias magnetic field generator that can be used.

[0006]

To achieve the above object, the present invention provides a magnetic field generating means for applying a magnetic field to a magnetic recording medium having a magnetic film, and an optical pickup for irradiating the magnetic recording medium with an optical beam. In a bias magnetic field generator for use in a magneto-optical recording device for recording information by irradiating an optical beam while applying a magnetic field to a magnetic recording medium, the magnetic field generating means are arranged in parallel in a linear direction. A plurality of coil winding devices,
A coil body wound around the coil winding device, a magnetic recording medium facing device formed so as to connect each end of a plurality of coil winding devices, and a coil winding from the vicinity of the magnetic recording medium facing device. A yoke portion formed so as to cover the side surface in a non-contact state is provided so as to be formed flat in the direction in which the coil winding equipment is juxtaposed to extend the magnetic recording medium facing tool in the movement direction of the optical pickup and the optical pickup. The width dimension in the direction orthogonal to the extending direction of the magnetic recording medium facing tool is formed to be longer than the moving distance, and the width dimension at the non-coupling point is smaller than the width dimension at the coupling point with the coil winding device. And a bias magnetic field generator.

[0007]

By thus dividing the coil body into a plurality of parts and forming the entire device flat, miniaturization can be realized, the magnetic recording medium facing portion is formed long, and the width is the width of the connecting portion with the coil winding device. By making it smaller, the magnetic field strength can be efficiently increased over the entire recording area.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a drive device using the present invention. On the lower surface of the bias field holder 1,
The bias magnetic field generator 2 is provided near the end in the X1 direction (close to the opposite end in the inserting direction of the magneto-optical disk cartridge 3),
Rectangular openings 4 are formed on both sides of the upper surface of the corresponding bias field holder 1 in the X1 direction, and a filter is provided as necessary although not shown. Further, vertically bent side walls 1a are formed on both sides of the bias field holder 1 in the Y direction, and two guide pins 5 projecting inward are attached to each side of the side walls 1a.

Below the bias field holder 1, a cartridge holder 6 is arranged. Cartridge holder 6
On the upper surface of the, the engaging pin 10, the lever 11, which operates along the guide grooves 8 and 9 formed in the cartridge holder 6 for opening and closing the shutter 7 of the magneto-optical disc cartridge 3. A shutter opening / closing device having a guide pin 12 and a torsion coil spring 13 is provided. A window 14 for receiving the bias magnetic field generator 2 is formed at a position corresponding to the bias magnetic field generator 2. Further, side walls 6a bent vertically are formed on both sides of the cartridge holder 6 in the Y direction, and the side wall 6a is formed on the side wall 6a.
Two guide grooves 15 with which the guide pin 5 engages are provided on each side, and further, one guide pin 16 is provided on each side of the side wall 6a so as to project outward.

A partition plate is provided below the cartridge holder 6.
17 are provided. A drive plate 18 is placed on the upper surface of the partition plate 17, and can be moved in the X direction via a cartridge guide pin 19 and a plate guide pin 20 provided on the partition plate 17. Then, after the drive plate 18 has moved in the X1 direction with respect to the partition plate 17, it can be returned to its original position by the spring 21 provided between the two. A trigger mechanism 22 is connected to the spring 21, and before the magneto-optical disc cartridge 3 is inserted, the engagement lever of the trigger lever provided rotatably via the shaft of the trigger mechanism 22. −22
By engaging a with the engaging groove formed in the drive plate 18, the drive plate 18 moved in the insertion direction of the magneto-optical disc cartridge 3 is fixed.
After the magneto-optical disc cartridge 3 is inserted, the trigger lever is rotated so that the engaging lever 22a is disengaged from the engaging groove and engaged with the end of the groove of the drive plate 18. The drive plate 18 moved in the ejecting direction of the disc cartridge 3 is fixed.

Further, a hole 23a having a substantially rectangular shape is formed at a position near the center of the partition plate 17 at a position opposite to the inserting direction of the magneto-optical disk cartridge 3 so that the cover does not come into contact with the optical head, which will be described later. , And a circular hole that is continuous with this so that the spindle motor turntable does not come into contact with it.
23b is formed. Also, at the bottom of the partition plate 17,
A loading drive device having a motor 24 for ding, a worm gear 25, and a cam 26 is provided.

A drive mechanism section and an optical deck section are provided below the partition plate 17. The optical deck portion is provided on a substantially box-shaped base 27 made of aluminum die cast, and an opening 28 for taking in air is formed in this base 27, and a filter 29 is attached to this. The writing drive switch 30 is provided on one side of the opening 28 in addition to the loading drive device. A VCM (voice coil motor) 31 has an inner yoke, an outer yoke, and a magnet, and a short pipe made of a copper material is wound to form a coil body to form a magnetic circuit. And movable optical head
Two magnetic circuits are arranged facing each other across 32,
A guide rail 33 extends in parallel between the two magnetic circuits, and the movable optical head 32 moves along the guide rail 33 along the X-axis.
You can move in any direction.

Coil bodies are fixed on both sides of the movable optical head 32 with respect to the Y direction by an adhesive, and a part of the coil body is positioned so as not to come into contact with the gap between the inner yoke and the outer yoke. By supplying an electric current to the coil body, a thrust is generated and the coil body moves. A fixed optical head 34 having a laser diode, a photodetector and the like is provided outside the base 27. Then, the light beam from the fixed optical head 34 has an opening 35 formed in the base 27 and the opening 35.
The objective lens 36, which passes through the cover glass 35a of FIG. 1, is reflected by a reflecting prism (not shown) provided in the movable optical head 32, and is moved by the actuator in the focusing direction and the tracking direction. It passes through and converges and reaches the magneto-optical disk as a light spot.

FIG. 2A is a front view of the bias magnetic field generator 2, and FIG. 2B is a sectional view taken along line AA of FIG.
(C) is a BB sectional view. The bias field holder 1 is made of a magnetic material. As shown in FIG. 1, the bias field holder 1 is formed with notches left on both sides in the Y direction, and is bent downward. Bend the tip further inward. The bent pieces thus formed are referred to as outer yokes 37 and 38. By bending a part of the bias field holder 1 to form the outer yokes 37 and 38 in this manner, a rectangular opening 4 is formed in the bias field holder 1 as shown in FIG. Becomes This opening 4 serves as an air inflow / outflow opening for radiating heat from the heat generating portion of the bias magnetic field generator 2.

Further, under the bias field holder 1 between the openings 4 facing each other, four coil winding equipments 39 are mounted separately in the X direction. A coil 40 is wound around each coil winding device 39, and a medium facing device 41 made of a magnetic material is fixed to the tip of the coil winding device 39 so as to connect the ends. The medium facing member 41 is formed long so as to face the entire recording area of the magneto-optical disk. Further, the dimension of the connecting portion 42 with the coil winding equipment 39 in the Y direction is S, and the connecting portion is
When the dimension in the Y direction of the medium facing member 41 between 42 is t, S>
It is formed to be t.

As described above, in the bias magnetic field generator 2 (FIG. 1) according to this embodiment, the outer yoke is formed by bending a part of the bias field holder, and the coil winding device is used as the bias field holder. Since the coil 40 is directly attached and the coil 40 is divided into a plurality of parts, the height direction of the bias magnetic field generator is flat, and the size can be reduced (FIG. 2B). Further, regarding the magnetic field strength on the surface of the recording medium, there is no inconvenience in the magnetic field strength in spite of the miniaturized configuration as described above. The point that the magnetic field strength can be efficiently increased in this embodiment will be described below. The Applicant has the above S = 1.8 and the above t = 1.27.
And the magnetic field strength on the surface of the recording medium when S = t were calculated by simulation. FIG. 3 shows the data. The measurement points are shown in Figure 2.
These are points 1 to 11 in (B).

In the present embodiment, as shown in FIG. 2A, the dimension S of the connecting portion 42 of the medium facing member 41 in the Y direction is set to Y between the connecting portions 42.
Since it is formed to be larger than the directional dimension t, the magnetic flux generated when a current is applied to the coil 40 is more likely to be concentrated in the center of the t dimension portion than the S dimension portion of the medium facing tool 41. The magnetic field strength with respect to is improved. Also,
Since the magnetic flux guided to the medium facing member 41 has a narrow width at the t dimension portion, it is difficult for the magnetic flux to travel in the X direction, and the magnetic flux easily travels in the Y direction and Z direction accordingly. Therefore, the magnetic flux efficiently advances toward the outer yokes 37 and 38, and the magnetic field strength with respect to the recording medium surface is improved.

At this point, when S = t, as shown in FIG. 3, the magnetic flux traveling from the coil winding device 39 toward the medium facing device 41 is in a coarse state over the entire width S of the medium facing device 41. Since it is guided, the magnetic field strength cannot be improved accordingly. Further, the magnetic flux guided to the medium facing tool 41 is likely to proceed in the X direction, and the magnetic flux is less likely to proceed in the Y direction and Z direction, and the magnetic field strength cannot be improved. In FIG. 3, the data having high magnetic field strength near the measurement points 4 and 10 is shown by the fact that the measurement point is the coil winding device 39.
This is because it corresponds to the position shown in FIG. 2 (B).

FIG. 4 shows a second embodiment of the present invention. FIG. 4 (A) is a front view, FIG. 4 (B) is an AA sectional view, and FIG. 4 (C) is. It is a BB sectional view. The parts corresponding to those in the first embodiment are designated by the same reference numerals. In this embodiment, projections 37a and 38a are formed on the outer yokes 37 and 38 near the connecting portion 42 of the medium facing tool 41, and the distance between the medium facing tool 41 and the outer yokes 37 and 38 is determined at which part. Are also configured to be approximately equidistant. That is, as shown in FIG. 4A, the distance m between the t dimension portion of the medium facing tool 41 and the outer yokes 37, 38, and the S dimension portion of the medium facing tool 41 and the outer yokes 37, 38. The distance n is set to be almost the same.

As shown in FIG. 5, generally, when the distance between the medium facing member 41 and the outer yoke 37 (38) is short, the magnetic flux advancing in the Y direction increases, so that the magnetic field strength in the Z direction at the measuring point is small. Become. Further, if the distance between the medium facing member 41 and the outer yoke 37 (38) is too long, the gradient of the magnetic flux in the Y direction at the measurement point becomes large, and the magnetic field strength in the Z direction becomes small. FIG. 5 is an explanatory view showing such a state in stages, FIG. 5A shows a case where the distance between the medium facing member 41 and the outer yoke 38 is short, and FIG. 5C shows a case where the distance is too long. ing. Therefore, the distance between the medium facing member 41 and the outer yoke 38 must be selected so as to be in the optimum state (FIG. 5B). In particular, when the shape of the medium facing member 41 is not constant in each part as shown in FIG. 4A, an optimum distance must be maintained according to the shape of each part.

Therefore, in this embodiment, as shown in FIG. 4A, the portion of the medium facing member 41 between the connecting portions 42 is farther from the outer yokes 37, 38 than the connecting portion 42. , The protrusions 37a, 38a so that the outer yokes 37, 38 come close to each other
Is formed. By configuring in this way, FIG.
When the magnetic field strength in the Z direction on the recording medium surface of the present embodiment and the first embodiment at the measurement point of (B) was obtained by simulation, it was as shown in FIG. Obviously, according to this example, it is found that an advantageous result is obtained in the magnetic field strength.

The present invention is not limited to the above embodiment, but various modifications and variations are possible. For example, although the coil winding device and the four coils are provided, the numbers are not limited. Further, the cross sectional shape of the coil winding equipment is not limited to a perfect circle, and may be any shape such as an elliptical shape.

As described above, according to the present invention, the outer yoke is formed by bending a part of the bias field holder, and the coil winding device is directly attached to the bias field holder. The height direction is flat, and downsizing can be realized. Further, by dividing the coil body into a plurality of pieces and reducing the number of coil turns, it is possible to realize flattening and downsizing of the device. Since it is possible to obtain an appropriate magnetic field intensity on the surface of the recording medium even with a short coil wire, power consumption is small and an increase in internal temperature of the device can be suppressed. Further, since the inductance can be reduced, the magnetic field reversal time can be shortened.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a drive device using the present invention.

FIG. 2 is a front view, an AA sectional view, and a BB sectional view of a bias magnetic field generator according to the first embodiment.

FIG. 3 is an explanatory diagram showing magnetic field strength according to the first embodiment.

FIG. 4 is a front view, an AA sectional view, and a BB sectional view of a bias magnetic field generator according to a second embodiment.

FIG. 5 is an explanatory diagram showing the relationship between the gap between the medium facing member and the outer yoke and the magnetic field strength.

FIG. 6 is an explanatory diagram showing magnetic field strength according to the second embodiment.

[Explanation of symbols]

 1 Bias magnetic field holder 4 Opening 37 Outer yoke 38 Outer yoke 39 Coil winding device 40 Coil 41 Medium facing device 42 Connection part

Claims (1)

Claim: What is claimed is: 1. A magnetic recording medium comprising magnetic field generation means for applying a magnetic field to a magnetic recording medium having a magnetic film, and an optical pickup for irradiating the magnetic recording medium with an optical beam. In a bias magnetic field generating device used in a magneto-optical recording device for irradiating an optical beam while applying the magnetic field, a magnetic field generating means includes a plurality of coil winding devices arranged in a straight line direction, and the coil winding device. A coil body wound around a winding device, a magnetic recording medium facing device formed so as to connect each end of a plurality of coil winding devices, and a non-contact from the vicinity of the magnetic recording medium facing device to the side surface of the coil body. And a yoke portion that is formed so as to cover in contact with each other, and is formed flat in the direction in which the coil winding equipment is juxtaposed, so that the magnetic recording medium facing tool extends in the moving direction of the optical pickup and Too long And a width dimension in a direction orthogonal to the extending direction of the magnetic recording medium facing tool is characterized in that the width dimension at the non-coupling point is smaller than the width dimension at the coupling point with the coil winding equipment. Generator.