JPH0685228B2 - Disk player optical head device - 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 for a disc player, in which a light beam is made incident on a disc through an objective lens and focus control and tracking control of the light beam incident on the disc are performed.

[0002]

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

In such an optical head device, for example, as shown in a simplified form in FIG. 5, the entire device including the semiconductor laser 61 and the photodetector 70 is integrally configured as one unit, and the disc D It is possible to move along the radial direction of. 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 shown by one line for simplification. The polarization beam splitter 63 has its optical axis direction changed and enters the collimator lens 64. Then, the laser light beam, which has been converted into a parallel light flux by the collimator lens 64, is made incident on the disc D through the objective lens 66, undergoes modulation in the recording track formed on the disc D, and is reflected.

The reflected laser light beam from the disk D is
It passes through the objective lens 66 and the collimator lens 64 in sequence and returns, passes through the polarization beam splitter 63 without changing its optical axis direction, and receives the light receiving lens (concave lens) 6
It is led to the photodetector 70 via 8. Then, the 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 related to the focus control drive unit 71 arranged in association with the objective lens 66.
And the tracking control drive unit 72, thereby causing the objective lens 66 to move along the optical axis of the disc D.
For the purpose of tracking control, a driving operation for focus control is performed to move the objective lens 66 toward or away from the optical disc, and the objective lens 66 is moved in the radial direction of the disk D that is a direction orthogonal to the optical axis of the objective lens 66. The driving operation is performed.

In the optical head device, a mechanism (hereinafter referred to as a biaxial drive unit) for performing such drive operation for focus control and drive operation for tracking control is configured as shown in FIG. 6, for example. It is assumed to have. The biaxial drive unit shown in FIG. 6 has a base 80 made of a metallic material which is fixed on a slide base which is movable in the radial direction of the disk.
A shaft 82 is erected at a substantially central portion of the base 80, and the shaft 82 is loosely inserted into a central hole formed in a central portion of a lens holding member 84 that holds the objective lens 66. Lens holding member 84 rotatable around 82
A cylindrical bobbin 86 is attached to the. A focus control coil 88 is wound around 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 arcuate magnetic yokes 92 are erected on the upper surface of the base 80 on which the shaft 82 is erected.
Further, the focus control coil 88 is attached to each magnetic yoke 92.
A pair of magnetic yokes 94 are provided at positions facing each other. Each magnetic yoke 94 is fixed to the upper surface of the base 80 via a magnet not shown in FIG.
Further, on the upper surface of the base 80, a pair of magnetic yokes 92
Lens holding member 84 in a direction orthogonal to the facing direction of
A pair of magnets 96 that face each other across the
It is supported and arranged by. The magnetic yokes 92 and 94, and the magnet and the magnet 96 arranged between the magnetic yoke 94 and the base 80 form a magnetic field forming unit for the focus control coil 88 and the tracking control coil 90. The focus control coil 88 wound around the bobbin 86 is positioned in a magnetic gap formed between the magnetic yoke 94 and the magnetic yoke 94 to form a focus control drive section, and each tracking control coil 90 is formed. A tracking control drive unit is formed so as to be arranged at a position facing each of the pair of magnets 96.

When the drive operation for focus control is performed by the biaxial drive unit thus constructed, the focus control signal is the focus control coil 8.
8 are 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 by the magnetic gap between the magnetic yoke 92 and the magnetic yoke 94, and the bobbin 86 extends along the shaft 82 erected on the base 80. The objective lens 66 is moved upward or downward to move the objective lens 66 in the direction along the optical axis thereof. On the other hand, when the drive operation for tracking control is performed, the tracking control signal is supplied to the tracking control coil 90. As a result, the pair of tracking control coils 90 receives 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. It is rotated clockwise or counterclockwise around the center, and moves the objective lens 66 in a direction orthogonal to its optical axis.

[0008]

In the optical head device as described above, usually, a pair of magnetic yokes 92 and a pair of magnet supporting portions 98 which form a base 80 and a magnetic field forming portion.
And the like are integrally formed, and a plurality of standing portions (magnetic yoke 92 and magnet supporting portion 98) are projected from a flat plate portion (base 80) as shown in FIG. 7, for example. Is used. And such a base 80
Base member 1 having an integrated structure of a magnetic yoke 92 and the like
00 is molded, for example, by casting using a mold formed by the lost wax method.

Thus, the base 80 and the magnetic yoke 92
Etc. are integrated, and when the base member 100 is molded by casting, the manufacturing cost increases, and not only the design constraint on the shape of the magnetic yoke 92 in the base member 100 becomes large. However, there is a problem that it is difficult to improve the accuracy of the base member 100.

In view of the above point, the present invention provides a magnetic yoke forming a magnetic field forming portion for a focus control coil and a tracking control coil in a biaxial drive unit, and a base supporting the magnetic yoke and the lens holding portion.
It is an object of the present invention to provide an optical head device for a disc player, which is obtained at a reduced manufacturing cost, has a large degree of freedom in design, and is improved in accuracy.

[0011]

In order to achieve the above object, an optical head device of a disc player according to the present invention holds an objective lens, and a focus control coil and a tracking control coil are attached to the optical head device. A lens holding member configured to be displaceable in a first direction along the optical axis and a second direction orthogonal thereto, and a magnetic field forming unit for supporting the lens holding member and for the focus control coil and the tracking control coil. A magnetic yoke member, wherein the magnetic yoke member is formed by bending the magnetic plate member to form at least a pair of first magnetic yoke members.
And a second set of bent uprights, each of which has a magnet attached to the first bent upright and a focus control for the first and second upright uprights. The coil and the tracking control coil are formed so as to be opposed to each other, and are attached to the base member together with the lens holding member so as to be positionally adjustable.

[0012]

In the optical head device of the disk player according to the present invention constructed as described above, the magnetic plate member is bent and has at least a pair of first and second bent standing pieces. The configured magnetic yoke member is positionally adjusted and fixed to a base member formed separately from the magnetic yoke member together with the lens holding member, and a pair of first and second bent uprights is provided. A magnet is attached to the first bent standing piece in each of the pair of pieces to form a pair of magnetic field forming portions, and the lens holding member is formed by the magnetic yoke member.
The focus control coil and the tracking control coil are positioned and supported in the respective magnetic fields formed by the pair of magnetic field forming units. Then, under such a state, the focus control coil and the tracking control coil are respectively supplied with predetermined focus control signals and tracking control signals, whereby the objective lens held by the lens holding member is aligned with its optical axis. It is moved in the direction along and the direction orthogonal thereto.

As described above, the magnetic yoke member is formed by bending the magnetic plate member to provide a set of bent standing pieces for forming a magnetic field forming portion. The base member and the magnetic yoke member are attached to a separately formed base member so that their positions can be adjusted together with the lens holding member. For example, the base member and the magnetic yoke member are integrally formed by casting. Compared with the case, the manufacturing cost is reduced, the design restrictions of the magnetic yoke member and the base member are alleviated, and the accuracy is improved.

[0014]

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

In the example shown in FIG. 3, the laser light emitted from the semiconductor laser 1 is diffracted by the grating 2 into three laser light beams (in FIG. 3,
For simplicity, these three laser light beams are shown as a single line. ), Is reflected by the plate-shaped beam splitter 3 and enters the collimator lens 4. Then, the laser light beam converted into a parallel light flux by the collimator lens 4 is
It is made incident on the disk D through the objective lens 6, and is modulated and reflected 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 disk D is
After passing back through the objective lens 6 and the collimator lens 4 and then 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 the light receiving lens ( concave lens)
It is guided to the photodetector 10 via 8. Then, the 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 the focus control drive unit 11 and the tracking control drive unit 12 arranged in association with the objective lens 6, respectively, thereby causing the objective lens 6 to follow the optical axis thereof. The disk D in the direction to move toward or away from the disk D,
While the drive operation for focus control is performed,
A driving operation for tracking control is performed in which the objective lens 6 is moved in the radial direction of the disk D which is a direction orthogonal to the optical axis thereof.

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. The light beam generation / detection unit 14 is constituted, and the objective lens 6 and the focus control drive unit 1 are provided.
1 and the tracking control drive unit 12 are mechanically integrated into another block, and the biaxial drive unit 20
It is supposed 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 extend along the radial direction of the disk D.
It is attached to a slide base 18 which is guided and moved by 6.

In this way, a light beam generating / constituting an example of the optical head device of the disc player according to the present invention is formed.
Of the detection unit 14 and the biaxial drive unit 20, the biaxial drive unit 20 is configured, for example, as shown in FIGS. 1 and 2.

The example of the biaxial drive unit 20 shown in FIG. 1 is supposed to have a base 22 which is attached to the upper surface side of the slide base 18 shown in FIG. There is. This base 22 is
A through hole 22a is formed in the central portion thereof, and the through hole 22a is located directly above the through hole 18a provided in the slide base 18. On the upper surface side of the base 22, a magnetic yoke member 24 formed by processing a magnetic plate member into a metal plate is fixed by screws 26.

In the magnetic yoke member 24, a set of two sets of bent standing pieces 28a and 28b facing each other and a supporting bent standing piece 35 are provided on the magnetic plate member by bending. A magnet 30 is fixed to each bent standing piece 28a. Then, the bent standing pieces 28a and 28b and the magnet 30 together with a focus control coil and a tracking control coil, which will be described later, together with the focus control drive unit 1.
1 and the magnetic field forming portion forming the tracking control drive portion 12 are formed.

A long hole 32, through 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 minute hole for the base 22 is formed. The position can be adjusted. Further, in the magnetic yoke member 24, a pair of through holes 34 are formed in the vicinity of the elongated hole 32, and a pair of pins fitted into the through holes 34 and protruding 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 40a through which the pins 36 are inserted, and the lower surface thereof abuts the flanges of the pins 36, and the upper end edge of the fixed ends 40. And a pair of arm members 42, which are connected to the lower end edge via a hinge portion 42a and are swingable in a direction orthogonal to the guide shaft 16 shown in FIG. 4 (hereinafter, referred to as X-axis direction), and this pair. The upper end edge and the lower end edge are connected to the other end of each of the arm members 42 of the above through a hinge portion 42b, and the plate member 4 is swingable by the hinge portion 46a.
And 6 are provided. Then, the plate member 46
Is to be fitted into a notch portion 49 formed in the bobbin member 48 holding the objective lens 6.

The bobbin member 48 includes the lens fixing portion 50 to which the objective lens 6 is attached and the arm member 42 of the movable member 38 in a state where the plate member 46 of the movable member 38 is fitted into the cutout portion 49. It has a pair of side plate members 52 that form a space to be loosely inserted. And
The lens fixing portion 50 and the pair of side plate members 52 are formed with two sets of protruding portions 50a and 52a facing each other.
A focus control coil 54 wound in a cylindrical shape between each pair of the protrusions 50 a and 52 a, and the winding axis direction of the focus control coil 54 is the winding axis direction of the focus control coil 54. Tracking control coil 5 which is in close contact with the insulation so as to be orthogonal to
Five are arranged. That is, in this example, the movable member 38
The bobbin member 48 fixed to the movable member 38 constitutes a lens holding member for swingably holding the objective lens 6. Then, the bobbin member 48 moves the movable member 3
8, the movable member 38 is fixed to the pair of pins 36.
Is attached to the magnetic yoke member 24 via
The pair of focus control coils 54, together with the tracking control coils 55, are fitted to the bent standing 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, the focus control coil 54 and the tracking control coil 55 are connected to the focus control signal supply section and the tracking control signal supply section, 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 provided with a bobbin member 4 through a notch 49 formed in the bobbin member 48.
8 is guided to the lower surface side and fixed to a supporting bent upright piece 35 provided on the magnetic yoke member 24.

In the assembled state, 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 assembled. It has a mutual arrangement relationship as shown in FIG. 2, and is constituted by bent standing pieces 28a and 28b provided on the magnetic yoke member 24 and a magnet 30 fixed to the bent standing piece 28a. The focus control coil 54 and the tracking control coil 55 are positioned in a magnetic gap formed between the bent standing piece 28b and the magnet 30 in the magnetic field forming portion. And, as mentioned above,
The magnetic yoke member 24 is attached to the base 22 attached to the slide base 18 so that the position of the magnetic yoke member 24 can be adjusted with screws 26. Further, various members disposed on the base 22 are entirely transparent to a position corresponding to the objective lens 6. Hole 56a
Is covered with a case 56 formed with.

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

Further, when the driving operation for tracking control is performed, the tracking control signal is supplied from the tracking control signal supply section to the tracking control coil 55 through the flexible connection board 58, whereby the pair of tracking control coils 55. The bent standing pieces 28a and 28b provided on the magnetic yoke member 24.
And a magnetic field formed by a magnetic field forming section composed of a magnet 30 fixed to the bent upright piece 28a,
One of them is brought close to the magnet 30 facing it,
On the other hand, it receives an electromagnetic force depending on the polarity and level of the tracking control signal, which is made to be separated from the magnet 30 facing it. 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 portion 46a of the movable member 38 as a fulcrum, and as a result, the objective fixed to the bobbin member 48 is moved. The lens 6 is moved in the direction orthogonal to the optical axis direction thereof, that is, in the direction along the guide axis 16 shown in FIG. 4, in accordance with the tracking control signal.

[0028]

As is apparent from the above description, according to the optical head device of the disc player of the present invention, the focus control signal and the tracking control signal supplied to the focus control coil and the tracking control coil in the biaxial drive unit are provided. A magnetic yoke member forming a magnetic field forming unit for applying an electromagnetic force according to a signal is obtained by processing a magnetic plate body into a metal plate, and the magnetic yoke member is formed separately from the magnetic yoke member. Since the base member is attached to the base member together with the lens holding member for holding the objective lens in a positionally adjustable manner, for example, the base member and the magnetic yoke member are integrally formed by casting. Compared with the case where it is done, the manufacturing cost can be significantly reduced. Also,
The degree of freedom in designing the shapes and dimensions of the magnetic yoke member and the base member is increased, and the accuracy of the magnetic yoke member and the base member can be improved.

[Brief description of drawings]

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

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

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

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

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

[Simple explanation of symbols]

 6 Objective Lens 11 Focus Control Drive Unit 12 Tracking Control Drive Unit 14 Light Beam Generation / Detection Unit 20 Biaxial Drive Unit 22 Base 24 Magnetic Yoke Member 28a, 28b Bending Stand Piece 30 Magnet 38 Movable Member 48 Bobbin Member 54 Focus control coil 55 Tracking control coil

Claims (1)

[Claims] 1. A focus control coil and a tracking control coil are attached to hold an objective lens, and the objective lens is displaced in a first direction along an optical axis thereof and in a second direction orthogonal to the first direction. A lens holding member and a magnetic plate member that are bent to provide at least a pair of first and second bent upright pieces, and the first and second bent uprights are provided. In each of the set of pieces, a magnet is attached to the first bent standing piece, and the first and second bent standing pieces are made to face each other with the focus control coil and the tracking control coil sandwiched therebetween. A magnetic yoke member that forms the forming portion and supports the lens holding member, and a base member to which the magnetic yoke member is attached so that the position of the magnetic yoke member can be adjusted together with the lens holding member. The optical head device of the disc player.