JPH0419847A - Linear motor for magneto-optical disk device - Google Patents

Abstract

PURPOSE:To ensure a recording operation in a normal way by setting the magnets of the magnetic circuits provided at both sides of an objective lens in such a way where both magnets attract each other. CONSTITUTION:The magnets 4 and 4' of two linear motors 1 and 1' are set so as to attract each other. Thus a magnetic flux 10 leaked out of a center yoke 7' of the motor 1' is continuously connected to other leaked magnetic fluxes 10 which are sucked by a center yoke 7 of the motor 1. Therefore the fluxes 10 are set approximately parallel to the surface of a magneto-optical disk 11 in an area above the disk 11 positioned right above the middle point between both motors 1 and 1', i.e., an area above the disk 11 positioned right above an objective lens 6. As a result, the flux 10 never affect the vertical component of an external magnetic flux when the information is recorded with the external magnetic flux impressed vertically to the disk 11 while irradiating the laser light onto the preceding area above the disk 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a linear motor for a magneto-optical disk device, which is used for a seek operation of an optical pickup, etc. in a magneto-optical disk device.

[Conventional technology]

Magneto-optical disk drives use a seek operation to move an optical pickup to a predetermined track on a magneto-optical disk and stop it at that position, a focal lens operation to accurately focus an objective lens on the magneto-optical disk, and ,
It has a simple structure and is easy to control in order to perform tracking operations such as making the laser beam follow a predetermined track.
Moreover, near motors are often used due to their responsiveness.

FIG. 8 shows the configuration of a seek linear motor used for the seek operation of the optical pickup.

The seek linear motor is composed of two linear motors 11 arranged to sandwich the optical pickup 5. The linear motor 1 is composed of a magnetic circuit 3 using a coil 2 and a magnet 4.゛ consists of a 3° magnetic circuit using a coil 2゛ and a magnet 4. The coils 2 and 2' are provided on both wings of the optical pick amplifier 5, and the objective lens 6 that focuses the laser beam is
The optical pickup 50 is arranged on a line passing through the center of gravity and perpendicular to the paper surface.

In the above configuration, the coil 2 of the linear motor 1°
・When a drive current is applied to the coil 2.2°, the coil 2.2° receives thrust in the horizontal direction in the figure from the magnetic circuit 3.3° according to Fleming's left-hand rule, and as a result, the optical pickup 5 changes the diameter of the magneto-optical disk. It is designed to be driven in the direction.

[Problem to be solved by the invention]

By the way, in a magneto-optical disk device, when recording information, as shown in FIG. recording layer 11 from the disk substrate 11a side.
b, and the external magnetic flux 1 is emitted from the magnetic head 16.
7 is applied perpendicularly to the recording layer 11b.

However, in the above conventional configuration, when the magnetic circuits 3 and 3' of the two linear motors 1' are arranged with the magnetic poles of the magnets 4 and 4 degrees facing each other as shown in FIG. The leakage magnetic flux 10 of 3.3 degrees collides near the center and is applied to the magneto-optical disk 11 in the perpendicular direction. Therefore, when recording information, the magnetic flux actually applied to the magneto-optical disk 11 is a superposition of the leakage magnetic flux lO from the magnetic circuit 3.3' on the external magnetic flux 17 applied from the magnetic head 16 (FIG. 9). The external magnetic flux 1
Depending on whether 7 faces upward or downward with respect to the magneto-optical disk 11, one will be strengthened and the other will be weakened.
The problem is that normal recording cannot be performed.

For this reason, this problem has been dealt with by increasing the external magnetic flux 17 to counteract the leakage magnetic flux 10 or by providing a magnetic shield to reduce the leakage magnetic flux 10 on the magneto-optical disk 11. The former causes an increase in the size of the magnetic head 16 or an increase in power consumption, while the latter causes an increase in the number of parts or an increase in weight.

[Means to solve the problem]

In order to solve the above-mentioned problem, the linear motor for a magneto-optical disk device of the present invention has a magnetic circuit including a magnet and a yoke and a coil on both sides of an objective lens that focuses a light beam and irradiates it onto a magneto-optical disk. In a linear motor for a magneto-optical disk device, which moves the objective lens in a predetermined direction relative to the magneto-optical disk by passing a driving current through the coil, the magnets of the magnetic circuit are arranged so that an attractive force acts on each other. It is characterized by being

[Function] According to the above configuration, the magnets of the magnetic circuit provided on both sides of the objective lens are arranged so that an attractive force acts on each other.
The leakage magnetic flux leaking from one magnetic circuit is sucked into the other magnetic circuit, and the leakage magnetic fluxes from the magnetic circuits on both sides are connected.

Therefore, at the light beam irradiation position on the magneto-optical disk corresponding to directly above the objective lens, the direction of the leakage magnetic flux becomes almost parallel to the surface of the magneto-optical disk. As a result, the leakage magnetic flux does not affect the external magnetic flux for recording perpendicular to the magneto-optical disk surface.

[Embodiment 1] An embodiment of the present invention will be described below based on FIGS. 1 to 4. Note that members having the same functions as those shown in the drawings of the conventional example are given the same reference numerals.

The configuration of a seek linear motor used in a magneto-optical disk drive to perform a so-called seek operation in which an optical pick amplifier is moved to a predetermined track on a magneto-optical disk and stopped at that position is shown in Figure 2. This is shown in a plan view and a longitudinal sectional view in FIG.

The seek linear motor is composed of two linear motors 1° arranged to sandwich an optical pickup 5, and the linear motor 1 has a coil 2 and a magnetic circuit 3.
The linear motor 1° consists of a coil 2° and a magnetic circuit 3.

The coils 2, 2 are provided on both wings of the optical pickup 5, and are loosely passed through the center yokes 7, 7' located on the optical pink amplifier 5 side of the magnetic circuits 3, 3', respectively.

In addition, rectangular parallelepiped magnets 4 are attached to the side yokes 8 and 8'.
・A gap 9 is formed between the magnet 4 and the center yoke 7, and a gap of 9° is formed between the magnet 4 and the center yoke 7.

In the seek linear motor of this embodiment, the magnets 4 and 4'
are arranged so that an attractive force acts on each other. In this embodiment, the magnet 4 is arranged so that the magnetic flux at the gap 9 is directed from the center yoke 7 to the magnet 4, so the magnetic flux at the gap 9' The magnet 4'' is arranged so as to face the center yoke 7' from the center yoke 7'.The objective lens 6 that focuses the laser beam is arranged on a line passing through the center of gravity of the optical pickup 5 and perpendicular to the plane of the paper. There is.

In the above configuration, the coil 2' of the linear motor 1''
When a driving current is applied to the gap 9 in the direction shown in FIG.
As mentioned above, the magnetic flux 10a' at 10° is directed from the magnet 4' to the center yoke 7', so the coil 2° receives a thrust to the right in the figure according to Fleming's left-hand rule. Regarding the linear motor 1, when a driving current is applied to the coil 2 (FIG. 2) in a predetermined direction, the coil 2 receives a thrust of the same magnitude in the same direction as the thrust of the coil 2'. These thrusts act on the center of gravity of the optical pickup 5, and as a result, the optical pickup 5 (Fig. 2) is driven in the radial direction of the magneto-optical disk along the longitudinal direction of the magnetic circuits 3. become. In this way, since the center of gravity of the optical pickup 5 is driven by the two linear motors 1, a moment of force around the center of gravity is less likely to act on the optical pickup 5, and rotational vibrations are less likely to occur. Similarly, rotational vibration is less likely to occur in the objective lens 6 disposed above the center of gravity of the optical pickup 50. Therefore, the seek operation becomes stable.

In the seek linear motor of this embodiment, the magnets 4 and 4 of the two linear motors 1' are arranged so that they exert an attractive force on each other, so as shown in FIG. The leakage magnetic flux 10 leaking from the center yoke 7' of the linear motor 1 is continuously connected to the leakage magnetic flux 10 sucked into the center yoke 7 of the linear motor 1. For this reason,
The area on the magneto-optical disk 11 located directly above the midpoint of the linear motor 1', that is, the objective lens 6 (second
In the area on the magneto-optical disk 11 located directly above the area shown in FIG.

Therefore, when recording information by applying perpendicular external magnetic flux to the magneto-optical disk 11 while irradiating this area with a laser beam, the leakage magnetic flux 10 (Fig. 1) is relative to the perpendicular component of the external magnetic flux. Has almost no effect.

By the way, as shown in Figure 1, a magnetic circuit 3.3゛ with a length of 55 mm, a width of 13 mm, a height of 10 mm and a magnetic flux density of 4000 Gauss at the gap 9.9' is connected at 53 mm intervals, and magnets 4.4゛ are connected as shown in Figure 1. When arranged so that mutual attraction acts, the vertical component of the leakage magnetic field IO at the position of the magneto-optical disk 11 directly above the midpoint of the magnetic circuit 3.3° was measured with a Gaussmeter and found to be 5 Gauss. On the other hand, the 10th
As shown in the figure, when magnets 4.4 degrees are arranged so that repulsive force acts on each other, the leakage magnetic field 1 at the position of the magneto-optical disk 11
The vertical component of 0 was 45 Gauss. That is, according to the present invention, the vertical component of the leakage magnetic field 10 is reduced to 1/9.

[Example 2] Another example of the present invention will be described below based on FIGS. 5 and 6. For convenience of explanation, members having the same functions as those shown in the drawings of the above-described embodiments are denoted by the same reference numerals, and their explanations will be omitted.

The configuration of a seek linear motor used in a magneto-optical disk device is shown in a plan view in FIG. 5 and a joint sectional view in FIG. 6.

This seek linear motor corresponds to the seek linear motor of the embodiment described above, in which the magnetic circuits 3 and 3'' of the linear motor 1 are arranged by rotating them by 90 degrees.

The magnets 4 and 4' are arranged so that an attractive force acts on each other. For example, if the magnet 4 is arranged so that the magnetic flux at the gap 9 is directed from the center yoke 7 to the magnet 4, the magnetic flux at the gap 9° The magnetic flux is from magnet 4' to center yoke 7'
The magnet 4 is arranged so as to face.

By arranging the magnets 4 and 4 in this way, the leakage magnetic flux leaking from the center yoke 7 of the linear motor 1 is continuously connected to the leakage magnetic flux sucked into the center yoke 7 of the linear motor 1. . For this reason,
In the region on the magneto-optical disk located directly above the midpoint of the linear motor 1'', that is, in the region on the magneto-optical disk located directly above the objective lens 6, the leakage magnetic flux becomes almost parallel to the magneto-optical disk. .

Therefore, when recording information by applying perpendicular external magnetic flux to the magneto-optical disk while irradiating this region with a laser beam, the leakage magnetic flux has almost no effect on the perpendicular component of the external magnetic flux. Not affected.

[Embodiment 3] Another embodiment of the present invention will be described below based on FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the above-described embodiments are denoted by the same reference numerals, and their explanations will be omitted.

In a magneto-optical disk device, a tracking linear motor is used to control the position of the objective lens and perform a tracking operation in which the laser beam follows a predetermined track, and a tracking linear motor is used to accurately focus the objective lens on the magneto-optical disk. The configuration of the linear motor for force slinging used to perform force slinging operation according to
This is shown in the plan view of FIG.

The linear motor for tracking consists of a linear motor consisting of coils 2 and 2 and a magnetic circuit 3, and coils 2" and 2.
and a linear motor consisting of a magnetic circuit 3, and these two linear motors are provided so as to sandwich a holder 12 to which an objective lens 6 is fixed.

On the other hand, the focusing linear motor has coil 2
a, a linear motor consisting of a magnetic circuit 3, and a coil 2
a' and a linear motor consisting of a magnetic circuit 3', and these two linear motors are provided so as to pass through and sandwich the holder 12 to which the objective lens 6 is fixed.

The holder 12 to which the objective lens 6 is fixed is supported by an intermediate support 14 via leaf springs 13 for focus control, and the intermediate support 14 is supported by leaf springs 15 for tracking control. It is supported by a movable body (not shown).

The U-shaped magnetic circuits 3.3° are erected on the movable body, and the center yokes 7.7° pass through the holder 12 loosely. Magnets 4 and 4" have side yokes of 8 and 8 degrees, respectively.
The gears are fixed to the magnet 4 and the center yoke 7, and between the magnet 4'' and the center yoke 7'', respectively.
A pump 9.9 is formed. Then, on the upper end surface of the holder 12 in the gap 9, two coils 2 and 2 are attached.
is fixed thereto, and two coils 2' and 2' are similarly fixed on the lower end surface of the holder 12 within the 9° gap. Further, coils 2a and 2a' are fixed to the recesses of the holder 12 which are loosely penetrated by the center yokes 7 and 7'.

In this embodiment, the magnets 4 and 4'' are arranged so that they are attracted to each other, and in this embodiment, the magnet 4 is arranged so that the magnetic flux in the gap 9 is directed from the magnet 4 to the center yoke 7. The magnets 4' are arranged so that the magnetic flux at the gap 9' is directed at 4 degrees from the center yoke 7'.

In the above configuration, the objective lens 6 fixed to the holder 12 is moved in the tracking direction (horizontal direction in the figure) by applying a driving current to the coils 2, 2, 2', 2' of the linear motor for the tiger and king. is driven and tracking control is performed.

On the other hand, coil 2a of the linear motor for focusing
・By applying a driving current to 2a', the holder 12
The objective lens 6 fixed to is driven in the focusing direction (perpendicular to the plane of the paper) to perform focussing control.

In this embodiment, the magnets 4, 4' are arranged so that they are attracted to each other, so that the leakage magnetic flux leaking from the center yoke 7' is continuously connected to the leakage magnetic flux sucked into the center yoke 7'. Therefore, in the area on the magneto-optical disk located directly above the objective lens 6 provided approximately in the middle of the magnets 4, 4', the leakage magnetic flux becomes approximately parallel to the magneto-optical disk.

Therefore, when recording information by applying perpendicular external magnetic flux to the magneto-optical disk while irradiating this region with a laser beam, the leakage magnetic flux has almost no effect on the perpendicular component of the external magnetic flux. Not affected.

In this embodiment, a leaf spring support type objective lens holding method in which the objective lens 6 is held by leaf springs 13 and 15 was used, but even a fulcrum shaft type or four wire type objective lens holding method may be used. By similarly arranging the tracking linear motor and the focusing linear motor, the same effect as above can be obtained.

〔Effect of the invention〕

As described above, in the linear motor for a magneto-optical disk device of the present invention, the magnets of the magnetic circuits provided on both sides of the objective lens are arranged so that an attractive force acts on each other, so that leakage magnetic flux leaks from one magnetic circuit. is now absorbed into the other magnetic circuit, and the leakage magnetic fluxes from the magnetic circuits on both sides are connected. For this reason, at the light beam irradiation position on the magneto-optical disk that corresponds to directly above the objective lens, the direction of the leakage magnetic flux is almost parallel to the magneto-optical disk surface. Depending on whether the external magnetic flux is directed upward or downward, it will not be strengthened or weakened by leakage magnetic flux, allowing normal recording. This eliminates the need to increase external magnetic flux or provide a magnetic shield to counter leakage magnetic flux.
The magneto-optical disk device can be made smaller, lighter, and consume less power, and the magnet in the magnetic circuit can be strengthened to quickly drive the objective lens in a predetermined direction.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention. FIG. 1 is a schematic configuration diagram showing the arrangement of magnets in a magnetic circuit provided in a seek linear motor. FIGS. 2 and 3 are a plan view and a longitudinal cross-sectional view showing a schematic configuration of a seek linear motor. FIG. 4 is an explanatory diagram showing the operation of the linear motor. FIG. 5 and FIG. 6 show another embodiment, and are a plan view and a joint sectional view showing a schematic configuration of a seek linear motor. FIG. 7 shows another embodiment, and is a schematic diagram of a tracking linear motor and a force-shinging linear motor. 8 to 10 show conventional examples. FIG. 8 is a plan view showing a schematic configuration of the seek linear motor. FIG. 9 is an explanatory diagram showing how external magnetic flux is applied from the magnetic head to the magneto-optical disk. FIG. 10 is a schematic configuration diagram showing the arrangement of magnets in a magnetic circuit provided in the seek linear motor. 1.1゛ is a linear motor 2.2゛ ・2a is a coil, 3.3゛ is a magnetic circuit, 4.4° is a magnet, 6 is an objective lens, 7 is a center yoke, 8 is a side yoke, IO is a leakage 61 The bundle 11 is a magneto-optical disk. Patent applicant Sharp Co., Ltd.

Claims (1)

[Claims] 1. A magnetic circuit consisting of a magnet and a yoke and a coil are provided on both sides of an objective lens that condenses a light beam and irradiates it onto a magneto-optical disk, and a driving current is passed through the coil. A linear motor for a magneto-optical disk device that moves the objective lens in a predetermined direction with respect to a magneto-optical disk, wherein the magnets of the magnetic circuit are arranged so that an attractive force acts on each other. linear motor.