KR20050112010A - Optical pickup actuator and optical disc drive using the same - Google Patents

Abstract

At least one pair of electromagnetic fields in the focus room or the focus / tilt direction are generated by the action of a bobbin provided with a plurality of disclosed objective lenses movably supported on a base, a magnet installed on the base, and a magnetic field formed by the magnet. It comprises a coil unit having a first coil and a second coil for generating an electromagnetic force in the tracking direction. The coil unit is provided on at least one side of both sides in the tangential direction of the bobbin. The first and second coils are disposed on the same plane.

Description

Optical pickup actuator and optical disc drive using the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup actuator and an optical disk drive employing the optical pickup actuator, and more particularly, to an optical pickup actuator including a plurality of objective lenses for recording and / or reproducing a plurality of optical disks having different recording densities. One relates to an optical disc drive.

Digital versatile discs (hereinafter referred to as DVD: Digital Versatile Disc) are recorded and / or reproduced using light having a wavelength of 650 nm (or 635 nm) and an objective lens having a numerical aperture of 0.6 (0.65 in a recordable type). If the DVD has a diameter of 120 mm and a track pitch of 0.74 µm, the DVD has a recording capacity of 4.7 GB or more for the end face. DVD is insufficient as a recording medium for recording high definition (HD) class moving picture information. This is because recording of 135 minutes worth of moving picture information in high definition class requires, for example, a recording capacity of 23 GB or more for the end face. To meet this high density recording capacity requirement, high density optical discs, ie, Blu-ray optical discs with narrower tracks, by using light having a wavelength shorter than red, that is, blue light and an objective lens having a numerical aperture larger than 0.6 (e.g., 0.85). BD has been developed. Therefore, there is a need for an optical pickup actuator capable of driving a bobbin equipped with two objective lenses to record / reproduce information on DVD / CD and BD.

1 is a perspective view showing a conventional optical pickup actuator, Figure 2 is a perspective view showing the bobbin in detail.

Referring to FIG. 1, the base 10 on which the holder 11 is fixed, the bobbin 20 on which the first and second objective lenses 61 and 65 are mounted in the radial direction R, and one end thereof are provided. There is shown a support member (suspension 12) fixedly coupled to the bobbin 20 and the other end fixedly coupled to the holder 11 to movably support the bobbin 20. The bobbin 20 has an extension 23 extending in the tangential direction T from the main body 21. The space 25 is formed between the extension part 23 and the main body 21. The focus coil 41 is provided on the side surface 24 of the extension part 23, and the tracking coil 42 is provided on the side surface 22 of the main body 21. The base 10 is provided with magnets 31 and 32 for forming a magnetic circuit. The magnet 31 faces the focus coil 41, and the magnet 32 faces the tracking coil 42. The magnet 32 is installed in the space 25.

With this configuration, when a current is applied to the focus coil 41 and the tracking coil 42, electromagnetic forces in the focusing direction and the tracking direction are induced in the coils 41 and 42, respectively, so that the bobbin 20 moves in the focusing direction F. And in the tracking direction (R).

The optical pickup actuators shown in FIGS. 1 and 2 are located in different planes in which the focus coil 41 and the tracking coil 42 are spaced apart in the radial direction R. FIG. In order to form a magnetic field in each of the coils 41 and 42, two pairs of magnets 31 and 32 are spaced apart from each other in the tangential direction T. In order to secure the installation space of the coil 42 and the magnet 32, the bobbin 20 has a main body 21 and an extension portion 23 formed on the site 21 to form a space 25. Therefore, the size and weight of the bobbin 20 is increased, thereby lowering the driving sensitivity of the bobbin 20.

The bobbin 20 is required to be structurally stable. Extension 23 may inhibit the structural stability of the bobbin 20 to cause secondary resonance due to it. The secondary resonant frequency affects the recording / playback characteristics when the disc speed increases.

Since the magnet 32 is provided in the space 25, there is a possibility that the magnet 32 will collide with the magnet 32 when the bobbin 20 is driven. When the yoke 13 is provided in the space 25, the possibility of collision further becomes high. To avoid this, the space 25 should be made wider, which causes the second resonance due to the deterioration of the driving sensitivity and the structural instability of the bobbin 20 as described above. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above necessity, and provides an optical pickup actuator employing a bobbin equipped with a plurality of objective lenses and having improved driving sensitivity and recording / reproducing characteristics, and an optical disk drive employing the same. There is a purpose.

An optical pickup actuator of the present invention for achieving the above object comprises: a bobbin provided with a plurality of objective lenses for recording and / or reproducing optical discs having different recording densities, and movable on a base; A magnet installed in the base; At least one pair of first coils for generating electromagnetic force in one of a focus direction and a focus / tilt direction by an action of a magnetic field formed by the magnet, and a second coil for generating electromagnetic force in a tracking direction, and the bobbin A coil unit installed on at least one side of both sides of the tangential direction of the first and second coils, wherein the first and second coils are disposed on the same plane.

In one embodiment, the magnets are arranged adjacent to each other and have a polarization arrangement opposite to each other, and the magnets are provided adjacent to the first and second magnets, respectively, and the first and second magnets. And a third and a fourth magnet portion having opposite polarization arrangements, respectively, wherein the pair of first coils are positioned over the first, third magnet portion and the second and fourth magnet portions, respectively, Two coils are located across the first and second magnets.

In example embodiments, the plurality of objective lenses may include a first objective lens corresponding to a CD / DVD and a second objective lens corresponding to a BD. The first and second objective lenses are installed in the radial direction. Preferably, the second objective lens is installed on the outer circumferential side of the first objective lens. When the operating distance of the first objective lens is WD1 and the operating distance of the second objective lens is WD2, WD1 ≥ WD2, α = | WD1-WD2 | × (0.1 to 1.0), It is preferable to satisfy the condition that the separation distance to the optical disc = WD2 + alpha.

In one embodiment, the coil unit is an FP coil (fine pattern coil).

An optical disk drive of the present invention for achieving the above object is an optical disk drive having a spindle motor for rotating the optical disk, and an optical pickup actuator and moving in the radial direction of the optical disk to reproduce or record information recorded on the optical disk. An optical disc drive including a pickup and a control unit for servo of the optical pickup, wherein the optical pickup actuator is provided with a plurality of objective lenses for recording and / or reproducing optical discs having different recording densities and moving on the base. Possibly supported bobbins; A magnet installed in the base; At least one pair of first coils for generating electromagnetic force in one of a focus direction and a focus / tilt direction by an action of a magnetic field formed by the magnet, and a second coil for generating electromagnetic force in a tracking direction, and the bobbin A coil unit installed on at least one side of both sides of the tangential direction of the first and second coils, wherein the first and second coils are disposed on the same plane.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a perspective view showing an embodiment of the optical pickup actuator according to the present invention, Figure 4 is a perspective view showing in detail a movable portion including a bobbin.

3 and 4, the optical pickup actuator according to the present invention, the base 10, the holder 11 is installed, and the first and second objective lens 51, 52 having a different working distance Installed bobbin 100 and one end is fixedly coupled to the bobbin 100 and the other end is fixedly coupled to the holder 11 is provided with a support member (suspension: 12) for supporting the bobbin 100 to be movable.

The first and second objective lenses 51 and 52 are respectively used for recording and / or reproducing at least one kind of low density optical discs having different recording densities and optical discs (hereinafter, referred to as high density optical discs) having higher density than the low density optical discs. . The first objective lens 51 of this embodiment is for recording / reproducing DVD-based optical discs (hereinafter referred to as DVD) and CD-based optical discs (hereinafter referred to as CD) which are low density optical discs. The second objective lens 52 of this embodiment is for recording / reproducing BD, which is an optical disk having a higher density than DVD. The optical pickup actuator according to the present invention may also include three or more objective lenses having different working distances for recording and / or reproducing three or more kinds of optical disks having different recording densities.

The first and second objective lenses 51 and 52 are provided in the radial direction R. As shown in FIG. This is because the optical pickup employing the first and second objective lenses 51 and 52 moves in the radial direction R of the optical disc, thereby recording and / or reproducing the information signal.

Although the start positions (21 mm from the center of the optical disc) of the information area of the DVD / CD and BD are the same, a stacking ring protrudes on the inner circumferential side (16.2 mm from the center of the optical disc) in the case of a CD. In the case of a CD, a recording surface is provided at a position 1.2 mm from the bottom of the optical disk. In the case of a DVD, a recording surface is provided at a position of 0.6 mm from the bottom of the optical disc. In the case of BD, a recording surface is provided at a position of 0.1 mm from the bottom of the optical disk. 5 shows the working distances WD1 and WD2 of the first and second objective lenses 51 and 52. The working distances WD1 and WD2 refer to the distances between the first and second objective lenses 51 and 52 and the bottom surface of the optical disk D when light is focused on the recording surface of the optical disk D. FIG. The second objective lens 52 has a numerical aperture NA that is larger than the numerical aperture NA of the first objective lens 51, and the operating distance WD2 of the second objective lens 52 has a first objective lens 51. It is smaller than the working distance (WD1) of). This means that the second objective lens 52 is located closer to the optical disk D than the first objective lens 51. If the second objective lens 52 is positioned on the inner circumferential side of the first objective lens 51, the second objective lens 52 may interfere with the stack ring when accessing the start position of the information area. Therefore, it is preferable that the second objective lens 52 is provided on the outer circumferential side in the radial direction R than the first objective lens 51. In the present embodiment, when the optical pickup is located at the innermost circumference of the optical disc D, the first objective lens 51 is positioned 21 mm from the center of the optical disc D, and the second objective lens 52 is the center of the optical disc D. It is installed to be positioned at 16.2mm from.

Due to the difference in working distance, the first and second objective lenses 51 and 52 are installed at different heights when they are installed in the bobbin 100. To this end, the bobbin 100 is provided with two installation holes 103 and 104 positioned in the radial direction R and stepped with each other, and the first and second objective lenses 51 and 52 are installed in the bobbin 100. 103 and 104, respectively.

In view of the driving clearance of the first and second objective lenses 51 and 52, the separation distance of the second objective lens 52 with respect to the optical disk D when the second objective lens 52 is not driven = It is desirable to satisfy the relationship of WD2 + α. Where α = | WD1-WD2 | x (0.1-1.0), and the working distance WD1 (WD2) is a relationship of WD1≥WD2. Then, as shown in FIG. 7, since the basic separation distance between the second objective lens 52 and the optical disk D becomes WD2 + α, the first objective lens having a large initial mounting and operating distance of the optical disk D is large. (51) During operation, contact (interference) between the second objective lens 52 having a small working distance and the optical disk D is prevented.

3 and 4, the coil unit 120 is installed at both side portions 102 of the tangential direction T of the bobbin 100. The base 10 is provided with a magnet 120 to face the coil unit 120. Reference numeral 140 is a yoke. The coil unit 120 includes a pair of first coils 160a and 160b and a tracking direction for driving in any one of a focus direction F and a focus F / tilt direction (Tt or Tt and Tr). A second coil 150 for driving R) is provided. The pair of first coils 160a and 160b are disposed in the radial direction R with the second coil 150 interposed therebetween. By such a configuration, the first coils 160a and 160b and the second coil 150 are installed on the same plane. It may be a bulk type coil made by winding a copper wire with the first and second coils 160a, 160b and 150. The coil unit 120 may be a fine pattern coil (FP coil) in which the first and second coils 160a, 160b, and 150 are formed. The FP coil is manufactured by patterning a coil shape on a film (or printed circuit board), and has a thin thickness, which may greatly contribute to reducing the weight of the movable part and miniaturizing the optical pickup actuator.

The magnet 130 interacts with the first and second coils 160a, 160b, and 150 to form the bobbin 100 in the focus direction F, the tilt direction Tt or Tt and Tr, and the tracking direction R. It has a polarization structure that can drive the movable part including the). Referring to FIG. 8, the magnets 130 are located adjacent to each other and have first and second magnet portions 131 and 132 having opposite polarization arrangements, and first and second magnet portions 131 and 132. And are polarized to form third and fourth magnet portions 133 and 134 which are adjacent to each other and have polarization arrangements opposite to the first and second magnet portions 131 and 132, respectively. The magnet 130 of the present embodiment is polarized such that the first to fourth magnet parts 131, 132, 133, and 134 have S, N, N, and S poles, respectively.

When the magnet 130 has a polarization structure as shown in FIG. 8, the first coil 160a has two sides 161 and 162 in the horizontal direction, respectively, and the first and third magnet parts 133 and 131, respectively. ), The first coil 160b is positioned such that the two sides 161 and 162 in the horizontal direction span the second and fourth magnet portions 134 and 132, respectively. The second coil 150 is positioned such that the two sides 151 and 152 in the vertical direction span the first and second magnet parts 131 and 132, respectively. The two sides 161 and 162 of the first coils 160a and 160b and the two sides 151 and 152 of the second coil 150 are in the focus direction F and the tilt direction Tt or Tt and Tr, respectively. )), The effective electromagnetic force for driving the tracking direction (R) is generated.

By such a configuration, when the current is supplied to the first coils 160a and 160b in different directions, the first coils 160a and 160b have the + focus direction (+ F) or the -focus direction (-F). The electromagnetic force is induced to drive the movable portion including the bobbin 100 in the focus direction F. FIG. When current is supplied to the first coils 160a and 160b in the same direction, electromagnetic forces in the focus directions (-F and + F or + F and -F) in opposite directions are induced to the first coils 160a and 160b. The movable part including the bobbin 100 is driven in the tangential tilt direction Tt. The movable part including the bobbin 100 is driven in the tracking direction R by inducing electromagnetic force in the + tracking direction (+ R) or the -tracking direction (-R) according to the direction of the current supplied to the second coil 150. do. It is also possible to drive in the radial tilt (Tr) direction by adjusting the direction of the current supplied to the first coils 160a and 160b of the two coil units 120 provided on both sides 102 of the bobbin 100. Do. By such a configuration, it is possible to implement an optical pickup actuator capable of two-axis, three-axis, and four-axis driving. It will be appreciated by those skilled in the art that the number of support members (suspension 12) for supplying current to each of the coils 160a, 160b, 150 will vary depending on which drive mode is employed.

Comparing the bobbin 100 of the present embodiment and the conventional bobbin 100 illustrated in FIG. 3, the bobbin 100 of the present embodiment may be implemented by only a portion corresponding to the main body 21 of the conventional bobbin 20. Do. Therefore, those skilled in the art will appreciate that the weight of the bobbin 100 is superior to the conventional bobbin 20 in terms of structural stability and enjoyment. Therefore, it is possible to improve the driving sensitivity of the optical pickup actuator and to prevent deterioration of recording / reproducing side by secondary resonance due to structural instability of the bobbin.

As described above, according to the optical pickup actuator according to the present invention, the weight of the bobbin 100 on which the plurality of objective lenses are mounted can be reduced, as well as structural stability, and excellent driving sensitivity can be obtained. Deterioration of recording / reproducing characteristics due to secondary resonance can be prevented.

9 is a view schematically showing the configuration of an optical disk drive employing an optical pickup actuator according to the present invention.

Referring to FIG. 9, an optical disc drive is installed so as to be movable in a radial direction of the optical disc D, and a spindle motor 240 for rotating the optical disc D to reproduce and / or record information recorded on the optical disc. The optical pickup 210, the drive unit 220 for driving the spindle motor 240 and the optical pickup 210, and a controller 230 for controlling the focus, tracking, and / or tilt servo of the optical pickup 210. ). Here, reference numeral 250 denotes a turntable, and 260 denotes a clamp for chucking the optical disk D to the spindle motor 240 together with the turntable 250. The optical pickup 210 includes an optical pickup optical system including objective lenses 51 and 52 for focusing light emitted from a light source onto an optical disc D, and two and three axes of the objective lenses 51 and 52. Or an optical pickup actuator according to the present invention for four-axis driving.

When the optical disc D is inserted into the optical disc drive, the type of the optical disc D inserted by the optical detector or a separate detection device provided inside the optical pickup is discriminated. When the determination of the type of the optical disc D is completed, the optical pickup is driven so that the objective lens corresponding to the type of the inserted optical disc D is in the proper position of the optical disc D. FIG. That is, if the inserted optical disc D is a BD, the second objective lens 52 is at a proper position on the optical disc D. If the inserted optical disc D is a DVD / CD, the first objective lens 51 is an optical disc. The optical pickup is driven to come to an appropriate position on (D).

The light reflected from the optical disc D is detected through a photodetector provided in the optical pickup 210 and photoelectrically converted into an electrical signal, and the electrical signal is input to the controller 230 through the driver 220. The driving unit 220 controls the rotation speed of the spindle motor 240, amplifies the input signal, and drives the optical pickup 210. The controller 230 sends the adjusted focus servo, tracking servo, and / or tilt servo command back to the driver 220 based on the signal input from the driver 220, whereby the optical pickup actuator according to the present invention is an objective lens. Focus, tracking, and tilt operations of 51 and 52 are implemented.

As described above, according to the optical pickup actuator according to the present invention, it is possible to reduce the weight of the bobbin on which the plurality of objective lenses are mounted, as well as to ensure structural stability, to realize excellent driving sensitivity, and to achieve secondary resonance. The degradation of the recording / playback characteristic can be prevented. Therefore, it is possible to implement an optical disc drive having excellent recording / playback characteristics.

It is to be understood that the invention is not limited to that described above and illustrated in the drawings, and that more modifications and variations are possible within the scope of the following claims.

1 is a perspective view showing a conventional optical pickup actuator.

Figure 2 is a perspective view showing in detail the movable portion of Figure 1;

3 is a perspective view showing an embodiment of the optical pickup actuator according to the present invention.

Figure 4 is a perspective view showing in detail the movable portion of FIG.

5 is a view showing an operating distance of the first and second objective lenses;

6 is a cross-sectional view taken along line II ′ of FIG. 4.

7 is a view showing a separation distance between an objective lens and an optical disk.

8 shows a polarization structure of a magnet.

9 is a block diagram showing an embodiment of an optical disk drive according to the present invention.

<Description of the symbols for the main parts of the drawings>

10 ...... Bass 11 ...... Holder

12 ...... Support member 51, 52 ...... First and second objective lenses

Bobbin 103, 104 ...... Installer

120 ...... Coil Unit 130 ...... Magnet

131, 132, 133, 134 ... first to fourth magnet parts

150 ... second coil 160a, 160b ... first coil

210 ...... Optical pickup 220 ...... Drive

230 ...... Control unit 240 ...... Spindle motor

Claims (10)

A bobbin provided with a plurality of objective lenses for recording and / or reproducing optical discs having different recording densities, and movably supported on a base; A magnet installed in the base; At least one pair of first coils that generate electromagnetic force in one of a focus direction and a focus / tilt direction by an action of a magnetic field formed by the magnet, and a second coil that generates electromagnetic forces in a tracking direction, and the bobbin It includes; coil unit is installed on at least one side of both sides of the tangential direction of the, The first and second coils are arranged on the same plane, the optical pickup actuator. The method of claim 1, The magnets are arranged adjacent to each other and have a polarization arrangement opposite to each other, and are provided adjacent to the first and second magnets, respectively, and opposite to the first and second magnets, respectively. A third and fourth magnet part having a polarization arrangement of The pair of first coils are positioned over the first, third and second magnets, respectively, and the second magnets, and the second coil is positioned over the first and second magnets, respectively. Pickup actuator. The method of claim 1, The plurality of objective lenses include a first objective lens corresponding to a CD / DVD and a second objective lens corresponding to a BD. The method of claim 3, And the first and second objective lenses are installed in a radial direction. The method of claim 4, wherein And the second objective lens is installed on an outer circumferential side of the first objective lens. The method of claim 3, When the operating distance of the first objective lens is WD1 and the operating distance of the second objective lens is WD2, WD1 ≥ WD2, α = | WD1-WD2 | × (0.1 to 1.0), And a condition of the separation distance of the second objective lens from the optical disk = WD2 + α. The method according to any one of claims 1 to 6, The coil unit is an optical pickup actuator, characterized in that the FP coil. And an optical pickup having a spindle motor for rotating the optical disk, an optical pickup actuator and moving in a radial direction of the optical disk to reproduce or record information recorded on the optical disk, and a control unit for servo of the optical pickup. In the optical disk drive, the optical pickup actuator, A bobbin provided with a plurality of objective lenses for recording and / or reproducing optical discs having different recording densities, and movably supported on a base; A magnet installed in the base; At least one pair of first coils for generating electromagnetic force in one of a focus direction and a focus / tilt direction by an action of a magnetic field formed by the magnet, and a second coil for generating electromagnetic force in a tracking direction, and the bobbin And a coil unit installed on at least one side of both sides of the tangential direction of the optical disc drive, wherein the first and second coils are disposed on the same plane. The method of claim 8, The magnets are arranged adjacent to each other and have a polarization arrangement opposite to each other, and are provided adjacent to the first and second magnets, respectively, and opposite to the first and second magnets, respectively. A third and fourth magnet part having a polarization arrangement of And the pair of first coils are positioned over the first, third and second magnets, respectively, and the second coil is positioned over the first and second magnets, respectively. drive. The method of claim 8, The plurality of objective lenses are provided in the radial direction of the optical disc and include first and second objective lenses corresponding to CD / DVD and BD, respectively, and the second objective lenses are installed on the outer circumferential side of the first objective lens. And an optical disc drive.