JP2880818B2 - Head drive for recording and reproducing information - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing head drive device used in an optical information recording / reproducing device for recording, reproducing or erasing information by irradiating a disk-shaped recording medium with a light beam. More particularly, the present invention relates to a driving device for driving a movable portion of a head for performing at least one of recording and reproduction by magnetic means.

[0002]

2. Description of the Related Art In an optical information recording device represented by an optical disk device, recording, reproduction or erasing is performed by using a device generally called an optical head. The optical head has an objective lens, a semiconductor laser, a collimating lens, a beam splitter, a photodetector, etc., irradiates a light beam from the semiconductor laser onto the optical disk through the collimating lens, the beam splitter and the objective lens, and outputs the light beam from the optical disk. The configuration is such that reflected light is guided to a photodetector via an objective lens, a beam splitter, and the like. A reproduction information signal, a focus error signal, and a tracking error signal are generated from the output of the photodetector.

The objective lens is driven by a head driving device in a direction perpendicular to the optical disk surface (focus direction) based on the focus error signal and in a direction parallel to the optical disk surface (tracking direction) based on the tracking error signal. You.

[0004] As a conventional head driving device, for example, in the device disclosed in Japanese Patent Application Laid-Open No. 1-192022, a focusing coil is wound around a lens holder for holding an objective lens, and the focusing coil is wound around an optical element containing various optical elements. The objective lens is driven in the focus direction by an electrokinetic converter arranged in a surface magnetic field of a focusing magnetic circuit including a yoke and a columnar magnet arranged on the block. The objective lens is driven in the tracking direction by an electrodynamic converter in which a tracking coil is disposed in a gap of a tracking magnetic circuit including a yoke disposed on both sides of the optical block and a magnet disposed below the yoke. It has a configuration.

In this configuration, since the yoke and the magnet constituting the tracking magnetic circuit are stacked in the focus direction, the space occupied by the magnetic circuit in the focus direction increases, and the entire head driving device becomes large. There is.

On the other hand, as another apparatus, magnets 83 and 84 are arranged between both ends of two yokes 81 and 82 arranged in parallel as shown in FIG. 8 to form a flat tracking magnetic circuit. There is known an electrokinetic converter in which a tracking coil 85 is disposed in a gap of a magnetic circuit, and drives an objective lens in a tracking direction T.

In such an electrodynamic converter, the size of the magnetic circuit in the focus direction F can be made smaller than that in Japanese Patent Application Laid-Open No. 1-192022. However, in order to increase the magnetic flux density in the air gap of the magnetic circuit in order to drive the tracking coil 85 at high speed, the air gap distance G must be reduced or the size of the magnets 83 and 84 in the focus direction must be increased. Conflicting conditions are required.

[0008]

As described above, in the head drive device in which the yoke and the magnet constituting the tracking magnetic circuit are stacked in the focus direction, the space occupied by the magnetic circuit in the focus direction increases. However, there is a problem that the entire head driving device becomes large, and in a head driving device in which a magnet is arranged between both ends of two yokes arranged in parallel to make the tracking magnetic circuit flat, a tracking coil is used. In order to increase the magnetic flux density in the air gap of the magnetic circuit in order to drive at high speed, there is a problem that contradictory conditions are required that the air gap distance must be reduced or the size of the magnet in the focus direction must be increased. there were.

Therefore, the present invention can reduce the space occupied by the magnetic circuit in the focus direction to reduce the size of the entire device, and can increase the magnetic flux density in the air gap of the magnetic circuit to increase the speed of a coil such as a tracking coil. An object of the present invention is to provide an information recording / reproducing head drive device that can be driven.

[0010]

In order to solve the above-mentioned problems, a head driving apparatus according to the present invention is provided with a head driving device for driving at least one of recording and reproduction of information. A magnetic circuit is composed of the first, second and third plate-shaped yokes arranged and the first and second permanent magnets having a substantially E-shaped cross section.

That is, the first permanent magnet has two magnetic poles of a first polarity and one magnetic pole of a second polarity,
The two magnetic poles having the polarities of are respectively joined to one end surfaces of the first yoke and the third yoke. The second permanent magnet also has two magnetic poles of the first polarity and one magnetic pole of the second polarity, and the two magnetic poles of the first polarity are opposite end faces of the first yoke and the third yoke. , And a magnetic pole of a second polarity is joined to the other end surface of the second yoke. Then, a coil (for example, a tracking coil) fixed to the movable portion of the head is arranged between the first, second, and third yokes, which are gaps in the magnetic circuit.

According to another aspect of the present invention, there is provided an information recording / reproducing head drive device having a rectangular shape arranged in parallel.
A plate-shaped first and second yoke, substantially approximately U-shaped
A magnetic circuit is constituted by the first and second permanent magnets.

That is, the first permanent magnet has two magnetic poles of first and second polarities, and these magnetic poles are respectively joined to one end surfaces of the first and second yokes in the longitudinal direction . Similarly, the second permanent magnet has two magnetic poles of the first and second polarities, and these magnetic poles are respectively joined to the other end faces in the longitudinal direction of the first and second yokes. Then, a coil fixed to the movable portion of the head is arranged between the gaps of the magnetic circuit, that is, between the first and second yokes.

[0014]

The head driving device thus constructed has a magnetic circuit configuration in which magnets are arranged at both ends of a yoke arranged in parallel. Therefore, if the magnetic circuit and the coil are used for tracking, the space occupied by the magnetic circuit in the focus direction is reduced.

Further, the shape of the E-shaped or U-shaped permanent magnet, particularly the length in the longitudinal direction of the yoke, is adjusted to such an extent that the respective portions of the magnetic circuit do not cause magnetic saturation, that is, the maximum magnetic flux density of the respective portions of the magnetic circuit. By doing so, the efficiency of the magnetic circuit can be increased without increasing the space occupied in the focus direction, and the tracking coil disposed in the gap of the magnetic circuit can be driven at high speed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a configuration of an information recording / reproducing head drive device according to a first embodiment of the present invention, and FIG.
It is sectional drawing which follows the -A line.

In FIG. 1, an objective lens 10 is for converging a light beam for irradiating an optical disk (not shown), and is held by a lens holder 11. The lens holder 11 is attached to a part of the moving optical system 13 via two upper and lower leaf springs 12a and 12b (12b not shown) provided substantially parallel to the optical disk. The moving optical system 13 is an illustration for changing an optical path so that a light beam from a fixed optical system, which will be described later, is incident on the objective lens 10 and reflected light returning from the optical disk to the objective lens 10 is guided to the fixed optical system. It does not have a mirror or the like.

On the side surface of the lens holder 11, the objective lens 10 is focused in the focus direction F (the optical axis direction of the objective lens 10).
Is wound around a focusing coil 14. The focusing coil 14 is arranged in the surface magnetic field of the columnar focusing magnets 15a and 15b. The focusing magnets 15a and 15b are provided in parallel along the tracking direction T (radial direction of the optical disk) so as to sandwich the lens holder 11 from both sides, and the tracking magnet circuits provided along the tracking direction T are also provided. It is adhered to upper yokes 16a and 16b which form a part. The focusing coil 14 forms an electrokinetic converter together with the focusing magnets 15a and 15b, and drives the objective lens 20 in the focusing direction F by translating the lens holder 11 via the leaf springs 12a and 12b. .

As shown in detail in FIG. 2, the tracking magnetic circuit includes the upper yokes 16a and 16b and the middle yokes 1a and 1b.
7a, 17b, lower yokes 18a, 18b, and tracking magnets 20a, 20b and 21a, 21b. One surface of a spacer 19 made of a non-magnetic material having a columnar shape is bonded to both ends in the longitudinal direction of the middle yokes 17a and 17b.
6a, 16b and the lower yokes 18a, 18b are adhered.

Here, the tracking magnets 20a, 20
b and 21a, 21b are made of permanent magnets having an E-shaped cross section. In this example, the upper and lower magnetic poles of the permanent magnet having an E-shaped cross section are S poles, and the magnetic pole at the center is an N pole. And
Tracking magnets 20a, 20b and 21a, 21
The end faces of the two upper and lower S poles of b are bonded to the longitudinal ends of the upper yokes 16a and 16b and the longitudinal ends of the lower yokes 18a and 18b, respectively. Tracking magnet 2
The gaps between the magnetic poles 0a, 20b and 21a, 21b correspond to the positions of the spacers 19.

A tracking coil 22 wound in a direction perpendicular to the tracking direction T and substantially parallel to the optical disk (not shown) is fixed to both sides of the moving optical system 13. The tracking coil 27 is connected to the upper yoke 16.
a, 16b, middle yokes 17a, 17b and lower yoke 1
It is arranged in the gap between 8a and 18b.

Accordingly, a tracking magnetic circuit comprising the upper yokes 16a, 16b, the middle yokes 17a, 17b, the lower yokes 18a, 18b, the tracking magnets 20a, 20b and 21a, 21b, and the tracking coil 2
2, a driving force in the tracking direction T is obtained.

The moving optical system 2 of the tracking coil 22
The bearing units 23a and 23b are fixed to the folded portion located on the side opposite to the side 3. The bearing units 23a and 23b are engaged with two guide shafts (not shown) arranged in parallel along the tracking direction. Thus, the moving optical system 13 can move only in the tracking direction.

On the other hand, an optical block 24, which is a fixed optical system, is arranged on an extension of the moving optical system 13 in the moving direction. The light beam 25 emitted from the optical block 24
Enters the moving optical system 13. As described above, the optical path of the light beam 25 incident on the moving optical system 13 is bent by 90 ° by the mirror and incident on the objective lens 10.

The optical block 24 includes a semiconductor laser as a light source, a collimating lens for converting light from the semiconductor laser into parallel light, a beam splitter for dividing an optical path of light incident on the optical disk and light reflected from the optical disk, and a light beam from the optical disk. It is composed of a photodetector or the like that detects reflected light.
Then, by processing the output of the photodetector, a focus error of the light beam with respect to the optical disk surface, an error signal indicating a tracking error of the light beam, and an information signal recorded on the optical disk are detected. .

In the information recording / reproducing head driving apparatus of this embodiment, the tracking magnets 20a, 20b and 21a, 21b are constituted by permanent magnets having an E-shaped cross section, and the S poles are the upper and lower magnetic poles thereof. The upper and lower yokes 16a and 16b and the lower yokes 18a and 18b and the middle yokes 17a and 17b
Are adhered to both ends in the longitudinal direction to form a tracking magnetic circuit.

Therefore, as compared with the conventional magnetic circuit in which the tracking magnet and the yoke are stacked in the focus direction, the space occupied by the magnetic circuit in the focus direction F is reduced, and the head drive device is downsized.

The magnetic flux density of the gap in the magnetic circuit can be increased by selecting the gap defined in the magnetic circuit by the spacer 19 to be the minimum distance that the tracking coil 22 can move.

Further, since the length L of the E-shaped permanent magnet in the tracking direction T can be freely selected, the length L is adjusted until the magnetic circuit parts do not cause magnetic saturation.
That is, by increasing each magnetic circuit portion to the maximum magnetic flux density, an extremely efficient magnetic circuit can be realized without increasing the occupied space in the focus direction F. This makes it possible to drive the tracking coil 22 and the moving optical system 13 at high speed.

Next, another embodiment of the present invention will be described. FIG. 3 is a cross-sectional view showing a tracking magnetic circuit according to a second embodiment of the present invention. A U-shaped permanent magnet is used as the tracking magnet 34 instead of the E-shaped permanent magnet in the first embodiment. ing. Along with this, the yoke also has a two-stage configuration consisting of an upper yoke 31 and a lower yoke 32, and a spacer 33 is interposed between both ends in the tracking direction of both yokes 31, 32. Then, a tracking coil 35 is disposed in a gap between the upper yoke 31 and the lower yoke 32. Therefore, this embodiment can provide the same effect as the previous embodiment.

According to this embodiment, the length L of the tracking magnet 34 in the tracking direction is different from that of the previous embodiment.
Are the same, the driving force in the tracking direction is smaller than in the previous embodiment, but the occupied space in the focus direction is smaller.

FIG. 4 is a sectional view showing a tracking magnetic circuit according to a third embodiment of the present invention, in which the spacer 19 in the first embodiment is removed and the upper yoke 16 is removed.
a, 16b, middle yokes 17a, 17b and lower yoke 1
8a, 18b and the tracking magnets 20a, 20b and
By adhering the tracking coils 22a and 21b to each other, a gap for disposing the tracking coil 22 is ensured.

FIG. 5 is a cross-sectional view showing a tracking magnetic circuit according to a fourth embodiment of the present invention. In FIG.
By bonding the lower yoke 32 and the tracking magnet 34, a gap for disposing the tracking coil 35 is ensured.

FIG. 6 is a perspective view showing a tracking magnet according to a fifth embodiment of the present invention. Instead of integrally forming an E-shaped permanent magnet, three plate-shaped permanent magnets are arranged in parallel. The magnets 61a, 61b, 61c are integrated with a yoke 62 made of a magnetic material by an adhesive. Here, the magnetization directions of the plate-like permanent magnets 61a, 61b, 61c are substantially perpendicular to the yoke 62, and the magnetization directions of the middle permanent magnet 61b are the upper and lower permanent magnets 61a, 61c.
The direction of magnetization is reversed. Even when the permanent magnet and the yoke are combined to form the tracking magnet having an E-shaped cross section, the same effect as that of the first embodiment can be obtained.

FIG. 7 is a perspective view showing a tracking magnet according to a sixth embodiment of the present invention. Instead of integrally forming a U-shaped permanent magnet, two plate-shaped permanent magnets are arranged in parallel. Magnets 71a and 71b are integrated with a yoke 72 made of a magnetic material by an adhesive. Here, the magnetization directions of the plate-like permanent magnets 71a and 71b are substantially perpendicular to the yoke 72 and opposite to each other. Even when the permanent magnet and the yoke are combined to form a tracking magnet having a U-shaped cross section, the same effects as in the second embodiment can be obtained.

The present invention is not limited to the above embodiment. For example, the shape of the tracking magnet is not limited to the E-shape or the U-shape, and may be appropriately changed according to the number of yokes.

Although the tracking magnetic circuit has been described as the magnetic circuit in the above-described embodiment, the present invention can be similarly applied to other magnetic circuits as long as the head driving device drives a movable portion of the head. In addition, the present invention can be variously modified and implemented without departing from the gist.

[0038]

According to the present invention, a magnet having a substantially E-shaped or U-shaped cross section is disposed at both ends of a yoke arranged in parallel to drive, for example, a tracking coil. With this configuration, the space occupied by the magnetic circuit in the focus direction can be reduced, and the size of the head drive device can be reduced.

Further, the shape of the E-shaped or U-shaped permanent magnet, particularly the length in the longitudinal direction of the yoke, is adjusted to such an extent that each part of the magnetic circuit does not cause magnetic saturation, ie, the maximum magnetic flux density of each part of the magnetic circuit. By doing so, the efficiency of the magnetic circuit can be increased without increasing the occupied space in the focus direction, and the coil disposed in the gap of the magnetic circuit can be driven at high speed. Therefore, if this magnetic circuit is used to drive a tracking coil, high-speed access and tracking can be performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of an information recording / reproducing head drive device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a sectional view of a tracking magnetic circuit according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a tracking magnetic circuit according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a tracking magnetic circuit according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view of a tracking magnet according to a fifth embodiment of the present invention.

FIG. 7 is a perspective view of a tracking magnet according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view of a conventional tracking magnetic circuit.

[Explanation of symbols]

14 Focus coils 15a, 15
b: Focusing magnets 16a, 16b: Upper yokes 17a, 17
b ... Middle yoke 18a, 18b ... Lower yoke 19 ... Spacer 20a, 20b, 21a, 21b ... Tracking magnet (E-shaped permanent magnet) 22 ... Tracking coil 31 ... Upper yoke 32 ... Lower yoke 33 ... Spacer 34 ... Tracking Magnet (U-shaped magnet) 35: tracking coils 61a, 61b, 61: plate magnet 62: yoke 71a, 71b: plate magnet 72: yoke

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/085 G11B 21/02-21/02 632 H02K 33/18 H02K 41/035

Claims (2)

(57) [Claims] An information recording / reproducing head driving device for driving a movable portion of a head for performing at least one of recording and reproducing of information, comprising: plate-like first, second and third plates arranged in parallel; A yoke, two magnetic poles of a first polarity and one magnetic pole of a second polarity, and the two magnetic poles of the first polarity are respectively joined to one end surfaces of the first yoke and the third yoke; less magnetic poles of the second polarity is bonded to one end surface of the second yoke
A first permanent magnet, two magnetic poles of a first polarity, and one magnetic pole of a second polarity, wherein the two magnetic poles of the first polarity are the first yoke and the third yoke. is joined to the other end face of each small magnetic poles of the second polarity is bonded to the other end surface of the second yoke
Characterized by comprising one second permanent magnet and a coil fixed to the movable part and arranged between the first, second and third yokes. Head drive. 2. An information recording / reproducing head driving device for driving a movable portion of a head for performing at least one of recording and reproducing of information, comprising: first and second rectangular plate-shaped yokes arranged in parallel; At least one substantially U-shaped magnetic pole having two magnetic poles of first and second polarities, each of which is joined to one longitudinal end surface of the first and second yokes, respectively.
A first permanent magnet has two magnetic poles of the first and second polarity, at least one substantially that these magnetic poles are respectively joined to the other longitudinal end surface of said first and second yoke Generally U-shaped
A second permanent magnet, fixed to the movable portion, and the first and second permanent magnets.
And a coil disposed between the yokes.