JP2002208153A - Optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head device, in which the efficiency of a magnetic driving circuit for magnetically driving an objective lens is improved and also the degree of freedom for layout can be increased. SOLUTION: In the optical head device, the magnetic driving circuit 6 is furnished with a pair of a focusing driving coil 60 and a tracking driving coil 65 arranged at both sides of an objective lens 3 of a lens holder 10, and a driving magnet 69 for generating crossed magnetic fluxes to these driving coils 60 and 65. For the driving coils 60, 65, the occupied rate of the effective part corresponding to the driving magnet 69 is formed to be larger compared with the occupied rate of the ineffective part.

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 used for recording and reproducing data on and from an optical recording medium.

[0002]

2. Description of the Related Art FIG. 7 is a schematic plan view showing a layout of a main part of a conventional optical head device. FIG. 8 is a plan view showing a lens holder used in a conventional optical head device and a configuration around the lens holder.

A conventional optical head device for recording and reproducing an optical recording medium such as a CD, a CD-R, and a DVD includes a laser light source 2 and a lens holding an objective lens 3, as shown in FIGS. Holder 10A and lens holder 10A
And a light guide system 30 that guides the laser light L emitted from the laser light source 2 to the objective lens 3;
It has a light receiving element 5 for detecting the return light from the optical recording medium, and a magnetic drive circuit 6A for driving the lens holder 10A in the focusing direction and the tracking direction, and these components are mounted on a frame 7A. ing.

The light guide system 30 includes a beam splitter 3 that partially reflects the laser light L emitted from the laser light source 2 at right angles.
1 and a rising mirror 32 that totally reflects the laser light L reflected by the beam splitter 31 upward and guides the laser light L to the objective lens 3. Therefore, the return light reflected by the optical recording medium is reflected by the rising mirror 32 toward the beam splitter 31 and then reflected by the beam splitter 3.
1 to the light receiving element 5. A pair of guide shafts 81 and 82 which engage with both ends of the frame 7A and guide the frame 7A in the radial direction of the optical recording disk are arranged in parallel.
Emits the laser beam L in parallel to these guide shafts 81 and 82. The positions of the laser light source 2 and the light receiving element 5 may be interchanged. In this case,
The laser light source 2 emits laser light L in a direction perpendicular to these guide shafts 81 and 82.

In the optical head device 1A thus configured, the magnetic drive circuit 6A includes a focusing drive coil 60A wound around an axis extending in the focusing direction with respect to the lens holder 10A, and the lens drive 10A. Focusing drive coil 6 at both end faces
A tracking drive coil 65A fixed on 0A,
A drive magnet 69A that generates a magnetic flux crossing these drive coils 60A and 65A.

[0006] In the magnetic drive circuit 6A configured as described above, the driving force on the lens holder 10A is proportional to the area of opposition between the drive coils 60A and 65A and the drive coil 69. For this reason, the focusing drive coil 60A is
It is wound substantially entirely in the height direction of the lens holder 10A.

However, in the conventional optical head device 1A, since the focusing drive coil 60A is wound substantially over the entire height of the lens holder 10A, the laser beam L cannot be made to enter the side of the lens holder 10A. . For this reason, the rising mirror 32 cannot be arranged inside the lens holder 10A. Therefore, since the rising mirror 32 must be disposed so as to overlap the lens holder 10A below the lens holder 10A, there is a problem that the height of the optical head device 1A cannot be reduced.

Japanese Patent Application Laid-Open No. H11-167736 discloses a lens having a pair of focusing drive coils 60C and a pair of tracking drive coils 65C disposed at both ends of a lens holder 10C as shown in FIG. There is disclosed an optical head device 1C in which a laser beam L can enter from the side of the holder 10C to the inside. According to the configuration disclosed therein, the rising mirror 32C can be arranged inside the lens holder 10C.

[0009]

In the magnetic drive circuit of the optical head device 1C shown in FIG. 9, of the focusing drive coil 60 and the tracking drive coil 65C,
A portion effective for driving the lens holder 10C is a portion facing the drive magnet 69C, and a portion not facing the drive magnet 69C is an invalid portion.

However, the optical head device 1 shown in FIG.
In the case of C, in both the focusing drive coil 60C and the tracking drive coil 65C, the ratio occupied by the effective portion is smaller than the ratio occupied by the ineffective portion. is there.

Further, in the optical head device 1C shown in FIG. 9, since the laser beam L needs to be incident on the lens holder 10C from directly in front to the inside, the layout described with reference to FIG. 7 must be adopted. Therefore, the size of the optical head device 1C cannot be reduced. That is, as shown in FIG. 7, when a layout in which the laser beam L travels parallel or perpendicular to the guide shafts 81 and 82 is adopted, the length of the optical path is directly applied to the length and width of the frame 7. Therefore, a large frame 7 must be used. Therefore, the optical head device 1C cannot be further reduced in size.

In view of the above problems, an object of the present invention is to
An object of the present invention is to provide an optical head device capable of improving the efficiency of a magnetic drive circuit for magnetically driving an objective lens and increasing the degree of freedom in layout.

[0013]

In order to solve the above problems, according to the present invention, a laser light source, a lens holder for holding an objective lens, and the lens holder are supported via a plurality of linear elastic support members. An optical head device comprising: a fixing member; a light guide system that guides laser light emitted from the laser light source to the objective lens; and a magnetic drive circuit that drives the lens holder in a focusing direction and a tracking direction. The circuit includes a pair of focusing drive coils wound around an axis extending in the focusing direction and a pair of tracking drive coils wound around an axis extending in the tracking direction on both sides of the lens holder sandwiching the objective lens. , Orthogonal to the tracking and focusing directions for these drive coils A driving magnet that generates a magnetic flux that intersects the driving coil on the drive side, wherein the focusing driving coil and the tracking driving coil have a dimension of an effective portion facing the driving magnet, and a dimension in a tracking direction and a focusing direction. It is characterized in that it is larger than the dimension of the ineffective portion directed in the direction perpendicular to the direction.

According to the present invention, in both the focusing drive coil and the tracking drive coil, the effective portion facing the drive magnet occupies a large proportion, so that the efficiency of the magnetic drive circuit is high and the weight of the drive coil is reduced. be able to. Therefore, high-speed driving can be performed. Further, in the present invention, since the drive coils are arranged on both sides of the objective lens in the lens holder, laser light can be made incident from the side of the lens holder to the inside, and the rising mirror of the light guide system can be connected to the lens holder. There is a high degree of design freedom in terms of layout, for example, it can be placed inside.

In the present invention, the lens holder includes, for example, a pair of flat focusing drive coil mounting portions extending in a focusing direction and a pair of flat tracking drive coils extending in a tracking direction on both sides of the objective lens. A mounting unit, wherein the focusing drive coil and the tracking drive coil are mounted on the focusing drive coil mounting unit and the tracking drive coil mounting unit, respectively.

Since the optical head device to which the present invention is applied has a high degree of freedom in design, the following configuration can be adopted. First, with respect to the lens holder, if the laser beam directed to the objective lens is configured to be able to enter a position below the objective lens between the pair of focusing drive coils and between the pair of tracking drive coils, A rising mirror that reflects laser light toward the objective lens can be arranged between the focusing drive coil and the pair of tracking drive coils. With this configuration, since the laser beam enters from the side of the lens holder, it is not necessary to arrange the rising mirror and the lens holder in an overlapping manner, so that the height of the optical head device can be reduced.

In the present invention, the lens holder is arranged so that the laser beam directed to the objective lens is moved in a tracking direction between the pair of focusing drive coils and between the pair of tracking drive coils to a position below the objective lens. On the other hand, it is preferable to be configured to be able to enter from an oblique direction. With such a configuration, the laser light source is engaged with both ends of the frame on which the laser light source, the fixing member, and the light guide system are mounted, and guides the frame in the radial direction of the optical recording disk. The laser beam can be emitted in an oblique direction with respect to the guide axis. When the optical path from the laser light source to the lens holder (objective lens) is set obliquely with respect to the guide axis, the length of the optical path does not directly affect the length and width of the frame. The whole can be effectively used, and the optical head device can be downsized. Also,
With an optical head device having the same dimensions, a light guide system or the like can be arranged with a high degree of freedom in design, and it is easy to arrange a plurality of light sources.

In the present invention, since a pair of focusing drive coils are arranged on both sides of the objective lens,
Even without adding a magnet dedicated to tilt control, tilt control for controlling the inclination of the lens holder with respect to the optical axis of the objective lens can be performed only by changing the energizing conditions for the pair of focusing drive coils.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing a layout of a main part of an optical head device to which the present invention is applied. FIG. 2 is a plan view showing a lens holder used in the optical head device shown in FIG. 1 and a configuration around the lens holder. FIG. 3 is a perspective view showing a configuration of a fixing member used in the optical head device shown in FIG. FIG. 4 is a perspective view showing a configuration of a lens holder and a drive coil used in the optical head device shown in FIG.

In FIG. 1, an optical head device 1 of the present embodiment is shown.
A laser light source 2, a lens holder 10 for holding the objective lens 3, a fixing member 4 for supporting the lens holder 10 via four linear elastic support members 21, 22, 23, 24; 2, a light guide system 30 for guiding the laser light L emitted from the optical lens 2 to the objective lens 3, a light receiving element 5 for detecting return light from the optical recording medium, and a magnetic drive circuit for driving the lens holder 10 in the focusing direction and the tracking direction. 6, and these components are mounted on the frame 7.

The light guide system 30 includes a beam splitter 3 that partially reflects the laser light L emitted from the laser light source 2 at right angles.
1 and a rising mirror 32 that totally reflects the laser light L reflected by the beam splitter 31 upward and guides the laser light L to the objective lens 3. Therefore, the return light reflected by the optical recording medium is reflected by the rising mirror 32 toward the beam splitter 31 and then reflected by the beam splitter 3.
1 to the light receiving element 5.

A pair of guide shafts 81 and 82 which engage with both ends of the frame 7 and guide the frame 7 in the radial direction of the optical recording disk are arranged in parallel.

In the present embodiment, the optical path of the laser light L is oblique to the guide shafts 81 and 82. That is, since the laser light source 2 emits the laser beam L in a direction oblique to the guide shafts 81 and 82, the laser light source 2 is raised from the laser light source 2 via the beam splitter 31 to the mirror 3
The optical path reaching 2 is set obliquely with respect to the guide shafts 81 and 82. The optical path of return light from the optical recording medium to the light receiving element 5 via the rising mirror 32 and the beam splitter 31 is also set obliquely with respect to the guide shafts 81 and 82.

As shown in FIG. 2 and FIG.
Is composed of a fixed frame 41 whose upper surface is open, and a circuit board 42 fixed to the fixed frame 41. The fixed frame 41 includes a substantially rectangular bottom wall 411, side walls 412, 413, and 414 surrounding three sides of the bottom wall 411, and the lens holder 1.
0, linear elastic support members 21, 22, 23, 24
And a mounting portion 415 for holding the base end portion of the main body.
The linear elastic support members 21, 22, 23, and 24 have a function of elastically supporting the lens holder 10 and a function of supplying power to the drive coils 60 and 65 on the lens holder 10. Therefore, the linear elastic support members 21, 22,
23 and 24 are passed two by two into two grooves 416 and 417 of the mounting portion 415 to which the insulating damper member 43 is mounted, and the end portions thereof are soldered to the circuit board 42. In the fixed frame 41, the bottom wall 4
From 11, four yokes 681, 682, 683, 684 to which the drive magnet 49 is fixed stand upright.

In the fixing member 4, a large notch 410 is formed from the center to one side of the side wall 412 where the laser beam L is incident and the return light from the optical recording medium is emitted. The notch 410 is formed in the bottom wall 411 around the area where the objective lens 3 is arranged.

On the other hand, as shown in FIGS. 2 and 4, the lens holder 10 has a lens holding portion 12 for holding the objective lens 3 in the center of a narrow upper plate 11. . The direction in which the upper plate 11 extends is the tracking direction (indicated by an arrow T), and the optical axis direction of the objective lens 3 is the focusing direction (indicated by an arrow F).

In the lens holder 10, the cylindrical portion 13 protrudes downward from the lens holding portion 12.
Laser light L is incident on the peripheral wall of the cylindrical portion 13,
The peripheral wall on the side from which the return light from the optical recording medium exits has a large opening 130 formed by partially cutting out the peripheral wall.

In the lens holder 10, a pair of focusing drive coil mounting portions 14 extending downward from both sides of the lens holding portion 12 are formed below the upper plate portion 11. In the lens holder 10, a pair of side plates 16 extend downward from both ends of the upper plate portion 11, and a pair of tracking drive coil mounting portions 15 protrude from the pair of side plates 16 in the tracking direction. I have.

A pair of focusing drive coil 60 and tracking drive coil 65 are mounted on each of the focusing drive coil mounting section 14 and the tracking drive coil mounting section 15 configured as described above. Therefore, the focusing drive coil 60
Is wound around an axis F1 extending in the focusing direction on both sides of the objective lens 3, and the tracking drive coil 65 is wound around an axis T1 extending in the tracking direction, and the drive coil 60 thus wound, Four drive magnets 69 are arranged at positions orthogonal to the focusing direction and the tracking direction. Here, since the drive magnet 69 is arranged so that both sides facing each other have the same polarity, there is no adverse magnetic effect on the opposing portions of the drive coils 60 and 65.

In the magnetic drive circuit 6 of the optical head device 1 thus configured, a portion of the focusing drive coil 60 and the tracking drive coil 65 that is effective for driving the lens holder 10 is a drive magnet 69.
The portion not facing the drive magnet 69 is a disabled portion. Therefore, in this embodiment,
As shown in FIG. 4, the focusing drive coil mounting unit 1
4 and the tracking drive coil mounting section 15 are such that the dimensions L11 and L21 of the effective portions facing the drive magnet 69 in the focusing drive coil 60 and the tracking drive coil 65 correspond to the invalid portions directed in the direction orthogonal to the tracking direction and the focusing direction. It is formed flat so as to be larger than the dimensions L12 and L22. Therefore, in the focusing drive coil 60 and the tracking drive coil 65, the proportion occupied by the effective portion facing the drive magnet 2 is larger than the proportion occupied by the ineffective portion in the direction orthogonal to the tracking direction and the focusing direction.

As described above, in the optical head device 1 according to the present embodiment, the ratio of the effective portion facing the drive magnet 69 in both the focusing drive coil 60 and the tracking drive coil 65 is large. Therefore, the efficiency of the magnetic drive circuit 6 is high and the drive coil 6
Since it is possible to reduce the weight of 0 and 65, high-speed driving can be performed.

Further, since the focusing drive coil 60 and the tracking drive coil 65 are flattened, the width dimension W when the focusing drive coil 60 and the tracking drive coil 65 are mounted on the lens holder 10 can be small, so that the layout surface can be reduced. High degree of freedom in design.

Further, since the drive coils 60 and 65 are arranged on both sides of the objective lens 3 in the lens holder 10, laser light can be incident from the side of the lens holder 10 to the inside, and the light guide system 30 can be set up. For example, the raising mirror 32 can be arranged inside the lens holder 10.
High degree of freedom in design in terms of layout.

That is, in the optical head device 1 of the present embodiment, the laser light L directed toward the objective lens 3 is applied between the pair of focusing drive coils 60 and between the pair of tracking drive coils 65 on the side surface of the lens holder 10. An opening 130 is formed to allow the light to enter the position below the objective lens 3, and the notch 4 is formed in the side wall 412 of the fixing member 4.
Since the mirror 10 is formed, the rising mirror 32 of the light guide system 30 is arranged inside the lens holder 10 (between the pair of focusing drive coils 60 and between the pair of tracking drive coils 65). Notch 41
The laser beam L incident from the aperture 0 and the opening 130 is guided to the objective lens 3 by the rising mirror 32. Therefore, since it is not necessary to arrange the rising mirror 32 and the lens holder 10 vertically, the optical head device 1
Can be reduced in height.

The notch 410 of the fixing member 4 and the opening 130 of the lens holder 10 are configured so that the laser beam directed toward the objective lens 10 can be incident from a direction oblique to the tracking direction to a position below the objective lens 3. Therefore, the laser light source 2 can be configured to emit the laser light L obliquely to a pair of guide shafts 81 and 82 for guiding the frame 7 in the radial direction of the optical recording disk. As described above, the optical path from the laser light source 2 to the lens holder 10 (the objective lens 3) is formed by the guide shafts 81 and 82.
If the angle is set to be oblique, the length of the optical path does not directly affect the length dimension and the width dimension of the frame 7.
The entire frame 7 can be effectively used, and the optical head device 1 can be downsized. Also, if the optical head device 1 has the same dimensions,
The light guide system 30 and the like can be arranged with a high degree of freedom in design, and it is easy to arrange a plurality of light sources.

[Other Embodiments] In the lens holder 10, as shown in FIG. 5, a cylindrical portion 18 extends upward from a central portion of a lower plate portion 17 having a small width. Alternatively, a configuration in which a lens holding unit 12 that holds the objective lens 3 may be formed. In this case as well, on the side of the peripheral wall of the cylindrical portion 18 where the laser light L is incident and the return light from the optical recording medium is emitted, an opening 130 is formed by cutting out a part thereof. Keep it.
Further, in the lens holder 10, a pair of flat focusing drive coil mounting portions 14 are formed above the lower plate portion 17 from both sides of the lens holding portion 12, and from both ends of the lower plate portion 17. A pair of side plates 16 are extended upward, and a pair of flat tracking drive coil mounting portions 15 are formed so as to protrude outward from each of the pair of side plates 16.

A pair of the focusing drive coil 60 and the tracking drive coil 6 are provided for each of the focusing drive coil mounting portion 14 and the tracking drive coil mounting portion 15 of the lens holder 10 thus configured.
5 respectively, the focusing drive coil 6
In both 0 and the tracking drive coil 65, the ratio of the effective portion facing the drive magnet 69 is large. Therefore, the same effects as those of the above-described embodiment can be obtained, for example, the efficiency of the magnetic drive circuit 6 is high.

In the above embodiment, FIG.
As shown in (A) and (B), when the wiring 190 is pulled out from the electrical connection point of the pair of focusing drive coils 60 using the flexible substrate 19 or the like, this wiring 1
The energization condition for the pair of focusing drive coils 60 can be changed depending on the potential applied to 90.
Therefore, the magnitude of the force applied to both ends of the objective lens 3 in the lens holder 10 can be changed without arranging a magnet or the like dedicated to tilt control, so that the inclination of the lens holder 10 with respect to the optical axis of the objective lens 3 ( (Tilt control) of the objective lens 3 can be controlled.

Further, in the above embodiment, the driving coil 60,
Although four drive magnets 69 are arranged for 65,
The number of drive magnets 69 may be reduced to two, and in this case, there is an advantage that the degree of freedom in layout is further increased.

[0041]

As described above, according to the present invention, the ratio of the effective portion facing the drive magnet to the lens holder in both the focusing drive coil and the tracking drive coil formed on both sides of the objective lens. Large, the efficiency of the magnetic drive circuit is high,
In addition, the weight of the drive coil can be reduced. Therefore, high-speed driving can be performed. Further, since the drive coils are arranged on both sides of the objective lens in the lens holder, laser light can be made to enter from the side of the lens holder to the inside. Therefore, since the rising mirror of the light guide system can be arranged inside the lens holder, the height of the optical head device can be reduced. Moreover,
Since the laser beam can enter the inside of the lens holder from an oblique direction, the optical path from the laser light source to the lens holder (objective lens) can be set obliquely with respect to the guide axis. There is also an advantage that the degree of freedom in design is high, such as the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a layout of a main part of an optical head device to which the present invention is applied.

FIG. 2 is a plan view showing a lens holder used in the optical head device shown in FIG. 1 and a configuration around the lens holder.

FIG. 3 is a perspective view of a fixing member used in the optical head device shown in FIG.

FIG. 4 is a perspective view showing a configuration of a lens holder and a drive coil used in the optical head device shown in FIG.

FIG. 5 is a perspective view showing a modification of a lens holder that can be used in the optical head device shown in FIG.

FIGS. 6A and 6B are a perspective view showing a state in which wiring for performing tilt control is drawn out in the optical head device shown in FIG. 1, and an equivalent circuit diagram for tilt control, respectively. .

FIG. 7 is a schematic plan view showing a layout of a main part of a conventional optical head device.

FIG. 8 is a plan view showing a lens holder used in a conventional optical head device and a configuration around the lens holder.

FIG. 9 is a perspective view showing a configuration of another lens holder and a drive coil used in a conventional optical head device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 optical head device 2 laser light source 3 objective lens 4 fixing member 5 light receiving element 6 magnetic drive circuit 7 frame 10 lens holder 11 lens holder upper plate portion 12 lens holding portion 14 focusing drive coil mounting portion 15 tracking drive coil mounting portion 17 fixing Lower plate portion of frame 19 Flexible substrate 21, 22, 23, 24 Linear elastic support member 30 Light guide system 31 Beam splitter 32 Start-up mirror 41 Fixed frame 42 Circuit board 42 Damper member 60 Focusing drive coil 65 Tracking drive coil 69 Drive Magnets 81, 82 Guide shaft 130 Lens holder opening 190 Wiring for tilt control 410 Cutout of fixed frame 411 Bottom wall of fixed frame 412, 413, 414 Wall of fixed frame 415 Mounting portion of fixed frame 416, 417 Fixed frame of 681,682,683,684 yoke L laser light

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsushi Hanaoka 5329 Shimosuwa-cho, Suwa-gun, Nagano F-term in Sankyo Seiki Seisakusho Co., Ltd. 5D118 AA01 AA13 BA01 BB02 DC03 EA02 EB13 ED00 ED08 EE05 EF09 FA29 FB20 FC06

Claims (6)

[Claims] 1. A laser light source, a lens holder for holding an objective lens, a fixing member for supporting the lens holder via a plurality of linear elastic supporting members, and a laser light emitted from the laser light source. A light guide system leading to the objective lens,
An optical head device having a magnetic drive circuit for driving the lens holder in a focusing direction and a tracking direction, wherein the magnetic drive circuit is wound around an axis extending in a focusing direction on both sides of the lens holder sandwiching the objective lens. A pair of focusing drive coils,
And a pair of tracking drive coils wound around an axis extending in the tracking direction, and a drive magnet for generating a magnetic flux that intersects the drive coils on the side orthogonal to the tracking direction and the focusing direction for these drive coils. Wherein the focusing drive coil and the tracking drive coil are characterized in that the size of an effective portion facing the drive magnet is larger than the size of an ineffective portion directed in a direction orthogonal to the tracking direction and the focusing direction. Optical head device. 2. The lens holder according to claim 1, wherein the lens holder has a pair of flat focusing drive coil mounting portions extending in a focusing direction and a pair of flat tracking drives extending in a tracking direction on both sides of the objective lens. An optical head device comprising: a coil mounting portion; wherein the focusing drive coil and the tracking drive coil are mounted on the focusing drive coil mounting portion and the tracking drive coil mounting portion, respectively. 3. The objective lens according to claim 1, wherein the lens holder is located at a position below the objective lens between the pair of focusing drive coils and the pair of tracking drive coils when the laser beam directed to the objective lens is located between the pair of focusing drive coils. The light guide system is between the pair of focusing drive coils, and between the pair of tracking drive coils,
An optical head device comprising: a rising mirror that reflects laser light toward the objective lens. 4. The lens holder according to claim 3, wherein the laser beam directed to the objective lens is disposed between the pair of focusing drive coils and between the pair of tracking drive coils to a position below the objective lens.
An optical head device, which is configured to be able to enter from an oblique direction with respect to a tracking direction. 5. The laser light source according to claim 4,
The laser beam engages with both ends of the frame on which the laser light source, the fixing member, and the light guide system are mounted, and the laser beam is oblique to a pair of guide shafts that guide the frame in the radial direction of the optical recording disk. An optical head device for emitting light. 6. The method according to claim 1, wherein
An optical head device, wherein a tilt control for controlling a tilt of the lens holder with respect to an optical axis of the objective lens is performed by changing an energizing condition for the pair of focusing drive coils.