JP2576442B2 - Optical head device for disc player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device of a disk player for making a light beam incident on a disk through an objective lens and performing focus control and tracking control on the light beam incident on the disk.

[0002]

2. Description of the Related Art An optical disk player for reproducing information from a disk-shaped recording medium is provided with an optical head device constituting an optical system for reading information from recording tracks formed on the disk-shaped recording medium.

In such an optical head device, for example, as shown in a simplified form in FIG. 5, the entire device including a semiconductor laser 61 and a photodetector 70 is integrally formed as one unit, and a disk D To be able to move along the radial direction. Then, the laser light emitted from the semiconductor laser 61 is diffracted by the grating 62 into three laser light beams (in FIG. 5, these three laser light beams are indicated by one line for simplicity). The direction of the optical axis is changed by the polarizing beam splitter 63 and the light enters the collimator lens 64. Then, the laser light beam converted into a parallel light beam by the collimator lens 64 is made incident on the disk D through the objective lens 66, and is reflected by being modulated on a recording track formed on the disk D.

[0004] The reflected laser light beam from the disk D is
The light passes back through the objective lens 66 and the collimator lens 64 in order, and passes through the polarizing beam splitter 63 without changing its optical axis direction.
The light is guided to the photodetector 70 through 8. Then, a detection output obtained from the photodetector 70 is supplied to a signal processing unit (not shown) to form a reproduction information signal, a focus control signal, and a tracking control signal. The focus control signal and the tracking control signal are respectively provided by a focus control driving unit 71 disposed in relation to the objective lens 66.
And is supplied to a tracking control drive section 72, thereby moving the objective lens 66 along the optical axis of the disc D.
A drive operation for focus control is performed to move the objective lens 66 closer to or away from the disk D, and the objective lens 66 is moved in a radial direction of the disk D, which is a direction orthogonal to the optical axis, for tracking control. The driving operation is performed.

In the optical head device, a mechanism (hereinafter, referred to as a two-axis driving unit) for performing such a driving operation for focus control and a driving operation for tracking control has, for example, a structure as shown in FIG. It is assumed to have. The biaxial drive unit shown in FIG. 6 has a base 80 made of a metal material fixed on a slide base movable in the radial direction of the disk.
A shaft 82 is erected substantially at the center of the base 80. The shaft 82 is loosely inserted into a center hole formed at the center of a lens holding member 84 that holds the objective lens 66. Lens holding member 84 rotatable about 82
, A cylindrical bobbin 86 is attached. A focus control coil 88 is wound on the outer peripheral surface of the bobbin 86, and a tracking control coil 90 is further disposed on the focus control coil 88 via an insulating film. The winding axis direction of the tracking control coil 90 is orthogonal to the winding axis direction of the focus control coil 88.

A pair of arc-shaped magnetic yokes 92 are erected on the upper surface of the base 80 on which the shaft 82 is erected.
Further, a focus control coil 88 is attached to each magnetic yoke 92.
A pair of magnetic yokes 94 are provided at positions facing each other with the. Each magnetic yoke 94 is fixed to the upper surface of the base 80 via a magnet not shown in FIG.
Further, a pair of magnetic yokes 92 are provided on the upper surface of the base 80.
A pair of magnets 9 opposed to each other with the lens holding member
6 are supported and arranged by the magnet support 98.
The magnetic yokes 92 and 94 and the magnetic yokes 9
The magnet and the magnet 96 arranged between the base 4 and the base 80 form a magnetic field forming part for the focus control coil 88 and the tracking control coil 90, and are formed between the magnetic yoke 92 and the magnetic yoke 94. The focus control coil 88 wound around the bobbin 86 is positioned in the magnetic gap to form a focus control drive unit. Each tracking control coil 90 is located at a position facing each of the pair of magnets 96. A tracking control drive section is formed.

When a driving operation for focus control is performed by the two-axis drive unit having such a configuration, the focus control signal is transmitted to the focus control coil 8.
8 is supplied. Thereby, the focus control coil 8
8 receives a force corresponding to the polarity and level of the focus control signal from the magnetic field formed in the magnetic gap between the magnetic yoke 92 and the magnetic yoke 94, and the bobbin 86 moves along the axis 82 erected on the base 80. To move the objective lens 66 in a direction along its optical axis. On the other hand, when a driving operation for tracking control is performed, a tracking control signal is supplied to the tracking control coil 90. Accordingly, the pair of tracking control coils 90 receive a force corresponding to the polarity and level of the tracking control signal from the magnetic field formed by the magnets 96 facing each other, and the bobbin 86 moves the shaft 82 erected on the base 80. The object lens 66 is rotated clockwise or counterclockwise as the center, and moves the objective lens 66 in a direction perpendicular to its optical axis.

In the optical head device having the two-axis drive unit configured as described above, the incident position of the light beam on the disk D through the objective lens 66 included in the two-axis drive unit is determined in the radial direction of the disk D. Will be moved along the radial direction of the disk D so as to be continuously displaced along.

[0009]

In the optical head device as described above, the base 80 and a pair of magnetic yokes 92 and a pair of magnet support portions 98 forming a magnetic field forming portion are usually provided.
The base member 100 is formed integrally with, for example, a plurality of standing portions (the magnetic yoke 92 and the magnet support portion 98) projecting from a flat plate portion (the base 80) as shown in FIG. Is used. And such a base 80
Member 1 having an integral structure of a magnetic yoke 92 and the like
The reference numeral 00 denotes a direction in which the central portions of the pair of magnetic yokes 92 oppose each other in a direction along the radial direction of the disk D on which the light beam passing through the objective lens 66 is incident. The facing direction may be a direction orthogonal to the radial direction of the disk D, for example,
It is formed by casting using a mold formed by the lost wax method.

Thus, the base 80 and the magnetic yoke 92
When the base member 100 is formed by casting, the manufacturing cost increases, and if the design constraints on the shape and the like of the magnetic yoke 92 in the base member 100 only increase, However, there is a problem that it is difficult to improve the accuracy of the base member 100.

Further, in the optical head device having a two-axis drive unit in which the base 80 and the magnetic yoke 92 are integrated, the incident position of the light beam on the disk D through the objective lens 66 is determined. When the whole of the disk D is moved in the radial direction so as to be continuously displaced in the radial direction, a driving mechanism for the entirety may be large and the occupied space may be increased. .

In view of the foregoing, the present invention provides a magnetic yoke constituting a magnetic field forming unit for a focus control coil and a tracking control coil in a two-axis drive unit including a lens holding member for holding an objective lens, and the magnetic field. The base member for supporting the yoke, the lens holding member, and the like is obtained at a reduced manufacturing cost, so that the degree of freedom in design is increased and the accuracy is improved. Drive mechanism for moving the disk along the radial direction of the disk on which the light beam enters through the objective lens is relatively small and occupies a relatively small space. I will provide a.

[0013]

An optical head device of a disk player according to the present invention holds an objective lens, has a focus control coil and a tracking control coil attached thereto, and moves the objective lens in a first direction along its optical axis. A lens holding member capable of being displaced in a second direction orthogonal to the first direction; a magnetic yoke member supporting the lens holding member and forming a magnetic field forming part for a focus control coil and a tracking control coil; A base member for the magnetic yoke member, and guide means for guiding the base member when the base member moves along the radial direction of the disk on which the light beam is incident through the objective lens, wherein the magnetic yoke member is a magnetic plate member Is bent to provide first and second bent upright pieces, and the first bent upright piece is provided with a magnet. When mounted, the first and second bent upstanding pieces can be located at positions facing each other across the focus control coil and the tracking control coil, and can be moved in the radial direction of the disk by being guided by the guide means. It is configured to be attached to the base member together with the lens holding member so that the position can be adjusted.

In the optical head device of the disk player according to the present invention configured as described above, the magnetic plate member is bent to provide the first and second bent upright pieces. Is formed separately from the base member, is fixed to a base member guided by the guide means and capable of moving in the radial direction of the disk with the lens holding member attached thereto, and is fixed to the first member. The magnet is attached to the bent upright piece and the magnetic field forming portion is formed by the first bent up piece and the second bent up piece, and the lens is held by the magnetic yoke member. In this state, the member is supported by positioning the focus control coil and the tracking control coil in the magnetic field formed by the magnetic field forming unit. Then, the predetermined focus control signal and the tracking control signal are supplied to the focus control coil and the tracking control coil, respectively, so that the objective lens held by the lens holding member moves in the direction along the optical axis and in the direction orthogonal thereto. Moved. At the same time, the base member moves in the radial direction of the disk under the guidance of the guide means, whereby the whole is moved in the radial direction of the disk.

As described above, the magnetic yoke member is formed by bending the magnetic plate member and providing the first and second bent upstanding pieces for forming the magnetic field forming portion. By being attached separately to the base member formed separately from the base member and guided by the guide means and capable of moving in the radial direction of the disk together with the lens holding member, For example, as compared with a case where a base member and a magnetic yoke member are integrated and molded by casting, manufacturing costs are reduced, and design restrictions on the magnetic yoke member and the base member are relaxed. The drive mechanism for moving the entire unit along the radial direction of the disk is relatively small and occupies a relatively small space. It will be.

[0016]

1 and 2 are an exploded perspective view and an external view showing an essential part of an example of an optical head device of a disk player according to the present invention, and FIG. 3 is a perspective view of the disk player according to the present invention. The whole of an example of an optical head device is simplified and shown.

In the example shown in FIG. 3, a laser beam emitted from a semiconductor laser 1 is diffracted by a grating 2 into three laser beams (in FIG. 3,
For simplicity, these three laser light beams are shown as one line. ), Reflected by the plate-shaped beam splitter 3 and incident on the collimator lens 4. Then, the laser beam converted into a parallel light beam by the collimator lens 4 is
The light is made incident on the disk D through the objective lens 6 and is reflected by being modulated on the recording track formed on the disk D. A focus control drive unit 11 and a tracking control drive unit 12 are arranged around the objective lens 6.

The reflected laser light beam from the disk D is
After sequentially passing through the objective lens 6 and the collimator lens 4 and returning and passing through the plate-shaped beam splitter 3, the correction glass plate 7 corrects the coma aberration received when passing through the plate-shaped beam splitter 3, and receives the light-receiving lens ( concave lens)
The light is guided to the photodetector 10 through 8. Then, a detection output obtained from the photodetector 10 is supplied to a signal processing unit (not shown) to form a reproduction information signal, a focus control signal, and a tracking control signal. The focus control signal and the tracking control signal are supplied to a focus control drive unit 11 and a tracking control drive unit 12, respectively, which are arranged in relation to the objective lens 6, thereby moving the objective lens 6 along its optical axis. In the direction to move closer to or away from the disk D,
Drive operation for focus control is performed,
A driving operation for tracking control is performed to move the objective lens 6 in the radial direction of the disk D, which is a direction orthogonal to the optical axis.

In this example, the semiconductor laser 1, the grating 2, the plate beam splitter 3, the collimator lens 4, the correction glass plate 7, the light receiving lens 8 and the photodetector 10 are mechanically integrated into one block. And constitutes the light beam generation / detection unit 14. The objective lens 6, the focus control drive unit 1
1 and the tracking control drive unit 12 are mechanically combined into one other block to form a two-axis drive unit 20.
It is assumed to constitute. As shown in FIG. 4, the light beam generation / detection unit 14 and the biaxial drive unit 20 are each a block housed in a case, and the guide shaft 1 extends in the radial direction of the disk D.
6 is attached to the slide base 18 which moves while being guided.

In this manner, the light beam generation and light constituting one example of the optical head device of the disk player according to the present invention is described.
Of the detection unit 14 and the two-axis drive unit 20, the two-axis drive unit 20 is configured, for example, as shown in FIGS.

The example of the biaxial drive unit 20 shown in FIG. 1 has a base 22 formed by, for example, zinc die-casting and attached to the upper surface side of the slide base 18 shown in FIG. I have. This base 22
A through hole 22a is formed at the center thereof, and the through hole 22a is located right above the through hole 18a provided in the slide base 18. A magnetic yoke member 24 formed by processing a magnetic plate member into a sheet metal is fixed to the upper surface side of the base 22 with screws 26.

In the magnetic yoke member 24, two sets of opposed bent upright pieces 28a and 28b and a supporting bent upright piece 35 are provided by bending a magnetic plate member. The magnet 30 is fixed to each bent upright piece 28a. Then, the focus control driving unit 1 together with a focus control coil and a tracking control coil to be described later are formed by the bent upright pieces 28a and 28b and the magnet 30.
1 and a magnetic field forming unit constituting the tracking control drive unit 12 are formed.

An elongated hole 32 into which the screw 26 is inserted is formed at a predetermined position of the magnetic yoke member 24. When the magnetic yoke member 24 is fixed to the base 22 by the screw 26, a fine hole with respect to the base 22 is formed. The position can be adjusted. Further, a pair of through holes 34 are formed in the vicinity of the elongated holes 32 in the magnetic yoke member 24, and a pair of pins which are inserted into the through holes 34 and protrude to the upper surface side of the magnetic yoke member 24. The movable member 38
Is attached.

The movable member 38 is formed with a pair of through holes 40 a through which the pins 36 are inserted, and has a fixed end 40 whose lower surface is in contact with a flange of the pin 36, and an upper end edge of the fixed end 40. A pair of arm members 42 connected to the lower end edge via a hinge portion 42a and swingable in a direction perpendicular to the guide shaft 16 shown in FIG. The upper end edge and the lower end edge are connected to the other ends of the arm members 42 via hinge portions 42b, respectively, and the plate-like member 4 which can be swung by the hinge portions 46a.
6 are provided. Then, the plate-like member 46
Is fitted in a notch 49 formed in a bobbin member 48 that holds the objective lens 6.

The bobbin member 48 includes a lens fixing portion 50 to which the objective lens 6 is attached, and an arm member 42 of the movable member 38 in a state where the plate member 46 of the movable member 38 is fitted in the notch 49. It has a pair of side plate members 52 that form a gap to be loosely inserted. And
The lens fixing portion 50 and the pair of side plate members 52 are formed with two sets of opposed protrusions 50a and 52a,
Between each pair of the projections 50a and 52a, a focus control coil 54 wound in a cylindrical shape, and the focus control coil 54 is wound in the direction of the winding axis of the focus control coil 54. And a pair of tracking control coils 55 which are insulated and adhered so as to be orthogonal to. That is, in this example, the movable member 38 and the bobbin member 48 fixed to the movable member 38 are used.
This constitutes a lens holding member for holding the objective lens 6 in a swingable manner. Then, with the bobbin member 48 fixed to the movable member 38, the movable member 38 is attached to the magnetic yoke member 24 via the pair of pins 36,
At this time, the pair of focus control coils 54 are fitted together with the pair of tracking control coils 55 to the bent upright pieces 28b provided on the magnetic yoke member 24.

On the upper end surfaces of the pair of side plate members 52 of the bobbin member 48, a focus control coil 54 and a tracking control coil 55 for connecting to a focus control signal supply unit and a tracking control signal supply unit, respectively. One end of a flexible connection substrate 58 formed by printing a lead wire on a polyimide resin thin film is fixed. The other end of the flexible connection board 58 is connected to the bobbin member 4 through a cutout 49 formed in the bobbin member 48.
The magnetic yoke member 8 is guided to the lower surface side and is fixed to a supporting bent piece 35 provided on the magnetic yoke member 24.

The magnetic yoke member 24 to which the magnet 30 is fixed, the movable member 38, the bobbin member 48, the focus control coil 54, the tracking control coil 55, and the flexible connection board 58 are in an assembled state. As shown in FIG. 2, the magnetic yoke member 24 has a mutual arrangement relationship, and is composed of bent upright pieces 28a and 28b provided on the magnetic yoke member 24 and a magnet 30 fixed to the bent upright piece 28a. The focus control coil 54 and the pair of tracking control coils 55 are located in a magnetic gap formed between the bent upright piece 28b and the magnet 30 in the magnetic field forming portion. Then, as described above, the magnetic yoke member 24 is attached to the base 22 attached to the slide base 18 so as to be position-adjustable by the screw 26. Further, the various members arranged on the base 22 are entirely attached to the objective lens 6 Are covered by a case 56 in which a through hole 56a is formed at a position corresponding to.

Under these circumstances, the base 22 and the slide base 18 to which it is attached are both mounted so that the magnetic yoke member 24 can be adjusted in position with the bobbin member 48 holding the objective lens 6, and the bobbin A base member to which the light beam generation / detection unit 14 which is a light beam generation means for emitting a light beam passing through the objective lens 6 held by the member 48 is formed. The guide shaft 16 serves as guide means for guiding the base member when the base member formed by the base 22 and the slide base 18 moves along the radial direction of the disk D on which the light beam passing through the objective lens 6 is incident. Has formed.

The two-axis drive unit 2 configured as described above
When the driving operation for focus control by 0 is performed, a focus control signal is supplied from the focus control signal supply unit to the focus control coil 54 through the flexible connection substrate 58, whereby each of the pair of focus control coils 54 In the magnetic field formed by the magnetic field forming portion constituted by the bent upright pieces 28a and 28b provided on the magnetic yoke member 24 and the magnet 30 fixed to the bent upright piece 28a, It receives an electromagnetic force according to the polarity and level of the focus control signal that is to be moved. Therefore, the bobbin member 48 to which the focus control coil 54 is fixed is moved in the X-axis direction together with the arm member 42 of the movable member 38. As a result, the objective lens 6 fixed to the bobbin member 48 It is moved in the axial direction according to the focus control signal.

When a driving operation for tracking control is performed, a tracking control signal is supplied from a tracking control signal supply unit to the pair of two pairs of tracking control coils 55 through the flexible connection board 58, whereby the tracking control signal is supplied. A pair of tracking control coils 55 forming two sets each include bent upright pieces 28 a and 28 b provided on the magnetic yoke member 24 and bent upright pieces 28.
In the magnetic field formed by the magnetic field forming part constituted by the magnet 30 fixed to a, one of them is brought close to the magnet 30 facing the other and the other is separated from the magnet 30 facing the same. Receiving an electromagnetic force according to the polarity and level of the tracking control signal. As a result, the bobbin member 48 to which the tracking control coil 55 is fixed via the focus control coil 54 is rotated about the hinge 46a of the movable member 38 as a fulcrum, and as a result, the object fixed to the bobbin member 48 is rotated. The lens 6 is moved in a direction perpendicular to the optical axis direction, that is, along a guide shaft 16 extending along the radial direction of the disk D shown in FIG.

[0031]

As is apparent from the above description, according to the optical head device of the disk player of the present invention, the focus control signal and the tracking control supplied to the focus control coil and the tracking control coil in the two-axis drive unit are provided. A magnetic yoke member constituting a magnetic field forming portion for applying an electromagnetic force according to a signal is formed by sheet metal processing of a magnetic plate body, and a first and a second magnet for attaching a magnet to constitute a magnetic field forming portion. The magnetic yoke member is formed separately therefrom, and can be moved in the radial direction of the disk by being guided by the guide means. The base member is attached to the base member so that the position can be adjusted together with the lens holding member. The manufacturing cost can be greatly reduced as compared with the case where a member formed integrally with a magnetic yoke member is used by casting, and in designing the shape or size of the magnetic yoke member and the base member. The degree of freedom is increased, the accuracy of the magnetic yoke member and the base member can be improved, and a relatively small drive mechanism for moving the entire unit in the radial direction of the disk is occupied. The space can be made relatively small.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view for explaining a configuration of a main part in an example of an optical head device of a disk player according to the present invention.

FIG. 2 is a perspective view of a main part of an example of the optical head device of the disc player shown in FIG.

FIG. 3 is a simplified configuration diagram showing an example of an optical head device of a disk player according to the present invention.

4 is an external perspective view of the example shown in FIG.

FIG. 5 is a simplified diagram showing an example of a conventional optical head device of a disc player.

6 is a perspective view of a main part in the conventional example shown in FIG.

FIG. 7 is a perspective view of a main part in the conventional example shown in FIG.

[Brief description of reference numerals]

 Reference Signs List 6 Objective lens 11 Focus control drive unit 12 Tracking control drive unit 14 Light beam generation / detection unit 16 Guide shaft 18 Slide base 20 Biaxial drive unit 22 Base 24 Magnetic yoke member 28a, 28b Bent upright piece 30 Magnet 38 Movable member 48 Bobbin member 54 Focus control coil 55 Tracking control coil D disk

Claims (3)

(57) [Claims] A focus control coil and a tracking control coil attached to the objective lens, the objective lens being displaced in a first direction along an optical axis thereof and in a second direction orthogonal to the first direction; A lens holding member configured to be capable of being bent, a magnetic plate member is bent to provide first and second bent upright pieces, and a magnet is attached to the first bent upright piece. A magnetic yoke member configured to form a magnetic field forming portion by the first and second bent upstanding pieces being opposed to each other with the focus control coil and the tracking control coil interposed therebetween, and to support the lens holding member; Light for emitting a light beam passing through an objective lens held by the lens holding member, wherein a magnetic yoke member is attached so as to be adjustable in position with the lens holding member. A base member to which a beam generating means is attached; and a guide means for guiding the base member when the base member moves in a radial direction of a disk on which a light beam passing through the objective lens is incident. Head device for disc player. 2. The magnetic yoke member according to claim 1, wherein third and fourth bent upright pieces facing the first and second bent upright pieces sandwiching the lens holding member are provided by bending. A magnet is attached to the third bent upright piece, and the third and fourth bent upright pieces are opposed to each other across the focus control coil and the tracking control coil to form a magnetic field forming section. The optical head device of a disc player according to claim 1, wherein 3. A base member on which a magnetic yoke member is mounted so as to be position-adjustable together with a lens holding member, and a beam generating means mounted on the base member, wherein the light beam from the light beam generating means is transmitted through the lens. 3. The optical head device for a disc player according to claim 1, further comprising a movable base attached to the objective lens held by the holding member so as to be incident on the objective lens.