JP2008217888A - Objective lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens driving device to be incorporated in an optical pickup device. <P>SOLUTION: Third and fourth focus coils 9c and 9d which are wound in hollow shapes so as to have winding axes in directions of optical axes of the objective lenses and are paired with first and second focus coils 9a and 9b juxtaposed in a tracking direction are provided on side faces of a lens holder 5 on both sides of objective lenses. Besides, first, second, third, and fourth magnets 11, 12, 13, and 14 disposed on the middle positions of the first, second, third, and fourth focus coils, a fifth magnet 16 disposed on the outside of the first and second focus coils in order to generate a magnetic flux acting on the first and second focus coils and a sixth magnet 17 disposed outside of the third and fourth focus coils in order to generate a magnetic flux acting on the third and fourth focus coils are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an objective lens driving device incorporated in an optical pickup device that performs a reading operation of a signal recorded on an optical disc and a recording operation of a signal on an optical disc.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reading operation and signal recording operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called CD or DVD has been widely used, but recently, an optical disk with improved recording density, that is, a Blu-ray standard or an HD DVD (High Density Digital Versatile Disk) standard. Those using optical discs have been developed.

  As a laser beam for performing an operation for reading a signal recorded on a CD standard optical disk, an infrared light having a wavelength of 780 nm is used, and a laser beam for performing an operation for reading a signal recorded on a DVD standard optical disk. In this case, red light having a wavelength of 650 nm is used.

  The protective layer provided on the upper surface of the signal recording layer in the CD-standard optical disc has a thickness of 1.2 mm, and an aperture of an objective lens used for performing a signal reading operation from the signal recording layer. The number is defined as 0.45. Further, the thickness of the protective layer provided on the upper surface of the signal recording layer in the DVD standard optical disc is 0.6 mm, and the numerical aperture of the objective lens used for performing the signal reading operation from the signal recording layer Is defined as 0.6.

  As a laser beam for performing a read operation of a signal recorded on an optical disc of the Blu-ray standard or the HD DVD standard with respect to the optical disc of the CD standard and the DVD standard, a laser beam having a short wavelength, for example, a wavelength of 405 nm Blue-violet light is used.

  The thickness of the protective layer provided on the upper surface of the signal recording layer in the Blu-ray standard optical disc is 0.1 mm, and the aperture of the objective lens used to read out signals from the signal recording layer The number is defined as 0.85.

As described above, optical discs with different standards have been proposed, and optical disc apparatuses that can use all optical discs have been commercialized. As a result, an optical pickup device incorporated in such an optical disc device is required to be compatible with optical discs of different standards. Optical pickup devices for meeting such requirements have been developed. (See Patent Documents 1 and 2.)
Further, as is well known, the optical pickup device has a housing in which optical components are incorporated, an objective lens is fixed, and a direction perpendicular to the signal surface of the optical disc by a support wire, that is, a focus direction and a radial direction of the optical disc, That is, a lens holder that is supported so as to be displaced in the tracking direction and has a focus coil and a tracking coil attached thereto, and a magnet that generates a magnetic flux acting on each coil and is fixed to a housing or the like. Yes. (See Patent Document 3)
JP 2005-182941 A JP 2004-259414 A JP 2002-245647 A

  The lens holder to which the objective lens is fixed is supported and fixed by the support wire so that it can be displaced in the focus direction and the tracking direction with respect to the objective lens support substrate constituting the objective lens driving unit. A focus coil and a tracking coil are attached. The focus coil and tracking coil are fixed to the side surface of the lens holder so as to be symmetric with respect to the objective lens.

  When the focus coil and the tracking coil are provided symmetrically with the objective lens interposed therebetween, the magnets that generate magnetic flux acting on these coils are also provided symmetrically with the objective lens interposed therebetween.

  The focus coil described in Patent Document 3 is mounted in a flat coil shape on the side wall of the lens holder in the same manner as the tracking coil. With such a configuration, there is a problem that not only the number of turns of the focus coil cannot be increased, but also the diameter of the winding cannot be increased, so that a large driving force cannot be obtained.

  In order to solve such a problem, it is conceivable to increase the focus drive current value supplied to the focus coil. However, if this is done, the amount of heat generation becomes large, which adversely affects the characteristics of the optical pickup device. Will occur.

  Also, by supplying drive current to the focus coil, the lens holder is displaced in a direction perpendicular to the signal surface of the optical disc, and focus control operation is performed. However, if the drive force is increased, unnecessary vibration called resonance occurs. There is a problem of doing.

  The present invention intends to provide an objective lens driving device capable of solving such a problem.

  According to the present invention, an objective lens is fixed and supported by a plurality of support wires so as to be capable of displacement in a tracking direction that is the radial direction of the optical disc and in a focus direction that is perpendicular to the signal surface of the optical disc, and a housing A tracking coil that generates a driving force in the tracking direction and the focusing direction by cooperating with a magnetic flux generated from a magnet fixed to the magnet, and a lens holder on which the focusing coil is mounted. The tracking coil includes the objective lens The focus coil is composed of first and second tracking coils fixed on the side surface of the lens holder with the objective lens interposed therebetween, and the focus coil is disposed on the side surface side of the lens holder with the objective lens in the optical axis direction of the objective lens. It is wound in a hollow shape with a winding shaft and is A third focus coil and a fourth focus coil paired with the first and second focus coils arranged side by side in the winding direction, and the magnets of the first, second, third and fourth focus coils In addition to the first, second, third, and fourth magnets arranged in the hollow position, they are arranged outside the first and second focus coils so as to generate magnetic fluxes that act on the first and second focus coils. The fifth magnet and a sixth magnet disposed outside the third and fourth focus coils so as to generate magnetic flux acting on the third and fourth focus coils.

  The present invention is characterized in that the tracking coil, the focus coil, and the magnet are arranged so as to be line-symmetric with respect to a straight line connecting the optical axis center of the objective lens and the rotation center axis of the optical disk.

  The present invention is characterized in that a first objective lens and a second objective lens for condensing laser beams of different wavelengths on signal recording layers provided on optical disks of different standards are incorporated in a lens holder. Is.

  Furthermore, the present invention is characterized in that the first objective lens and the second objective lens are arranged in the radial direction of the optical disc.

  Further, the present invention is characterized in that radial tilt adjustment can be performed by superimposing a radial tilt signal on a focus drive current supplied to a focus coil.

  The present invention provides a pair of tracking wires for supplying a tracking drive current to a tracking coil, a pair of focus wires for supplying a focus drive current to a focus coil, and a pair of radial tilt signals to be superimposed on the focus coil. The lens holder is supported by a tilt adjusting wire so as to be displaceable.

  In the present invention, the first and second coils are wound in a hollow shape so as to have a winding axis in the optical axis direction of the objective lens on the side surface side of the lens holder with the objective lens interposed therebetween, and are arranged in parallel in the tracking direction. First, second, third, and fourth magnets that are provided with third and fourth focus coils that are paired with the focus coil and that are disposed in the hollow positions of the first, second, third, and fourth focus coils. In addition, a magnetic flux acting on the third and fourth focus coils and a fifth magnet disposed outside the first and second focus coils to generate magnetic flux acting on the first and second focus coils. Since the sixth magnet disposed outside the third and fourth focus coils is provided to generate the driving force, not only the driving force for focusing operation can be increased, but also It is possible to prevent the resonance behavior of the holder by.

  In the present invention, the tracking coil, the focus coil, and the magnet are arranged so as to be symmetric with respect to a straight line connecting the optical axis center of the objective lens and the rotation center axis of the optical disk. The displacement operation and the displacement operation in the tracking direction can be performed with good balance.

  FIG. 1 is a perspective view of the main part showing the objective lens driving device of the present invention, and FIG. 2 is a plan view of the main part showing the objective lens driving device of the present invention.

  In the figure, reference numeral 1 denotes a printed wiring board fixed to a housing (not shown), and a pattern for supplying a focus driving current, a tracking driving current, and a radial tilt signal supplied from the optical disk apparatus is wired. 2a and 2b are a pair of tracking wires for supplying a tracking drive current to a tracking coil to be described later, 3a and 3b are a pair of focus wires for supplying a focus drive current to a focus coil to be described later, and 4a and 4b are radial tilt signals. A pair of tilt adjusting wires supplied to the focus coil, one end of which is fixed to the printed wiring board 1 by soldering.

5 is supported by the tracking wires 2a and 2b, the focusing wires 3a and 3b, and the tilt adjusting wires 4a and 4b so that the displacement operation in the focus direction, the displacement operation in the tracking direction, and the displacement operation in the radial tilt direction are possible. The first objective lens 6 for condensing the blue-violet laser light used for the Blu-ray standard optical disc and the infrared light used for the CD standard and DVD standard optical discs. The second objective lens 7 that performs the focusing operation of the red laser beam is fixed.

  The first objective lens 6 and the second objective lens 7 are arranged and fixed so that a straight line A (shown in FIG. 2) connecting the optical axis centers thereof coincides with the radial direction of the optical disk, that is, the radial direction. A laser diode that emits laser light incident on the first objective lens 6, an optical component that guides the laser light to the first objective lens, a laser diode that emits laser light incident on the second objective lens 7, An optical component or the like that guides the laser light to the second objective lens is provided in a housing (not shown), and is configured such that the laser light is incident from the side surface in the radial direction of the lens holder 5 from the arrow B direction. .

  Then, the laser light incident in this way is reflected by a reflection mirror called a raising mirror provided below the first objective lens 6 and the second objective lens 7 and then each objective lens from below. 6 and 7 to be incident. Since such a configuration is well known, its description is omitted.

  Reference numerals 8a and 8b denote first and second tracking coils which are bonded and fixed to the respective side surfaces of the lens holder 5 in a direction orthogonal to the tracking direction. It is formed in a flat shape so as to have.

  Reference numerals 9a and 9b denote first and second adhesive pieces fixed to side surfaces in a direction orthogonal to the tracking direction of the lens holder 5, that is, support pieces 5a and 5b provided on the side where the first tracking coil 8a is disposed. The second focus coil is provided side by side in the tracking direction and is wound in a hollow shape so as to have a winding axis in the optical axis direction of the objective lenses 6 and 7.

  9c and 9d are third and fourth adhesively fixed to the support piece 5c provided on the side surface in the direction orthogonal to the tracking direction of the lens holder 5, that is, on the side where the second tracking coil 8b is disposed. These focus coils are provided side by side in the tracking direction and are wound in a hollow shape so as to have a winding axis in the optical axis direction of the objective lenses 6 and 7.

  As described above, the first and second tracking coils 8a and 8b are fixed to the side surface of the lens holder 5, and the tracking drive current to the coils is electrically supplied through the tracking wires 2a and 2b. Connected. Similarly, the first, second, third and fourth focus coils 9a, 9b, 9c and 9d are fixed to the side surface of the lens holder, and the focus drive current to the coils is the focus wire. It is electrically connected to be supplied through 3a and 3b. The first, second, third and fourth focus coils 9a, 9b, 9c and 9d are electrically connected to the tilt adjusting wires 4a and 4b, and the tilt adjusting wires 4a and 4b are connected. A radial tilt signal is supplied via the.

  Reference numeral 10 denotes a first yoke fixed to the housing, and a first mounting piece 10a to which the first magnet 11 is bonded and fixed and a second mounting piece 10b to which the second magnet 12 is bonded and fixed are formed. Reference numeral 13 denotes a second yoke which is fixed to the housing and provided on the opposite side of the first yoke and the lens holder 5, and includes a first mounting piece 13a to which the third magnet 14 is bonded and fixed. A second mounting piece 13b to which the magnet 15 is bonded and fixed is formed.

In such a configuration, the first magnet 11 and the second magnet 12 include a hollow portion and a second portion provided in the first focus coil 9a together with the first mounting piece 10a and the second mounting piece 10b of the first yoke 10. The focus coil 9b is configured to be inserted into a hollow portion provided in the focus coil 9b. The third magnet 14 and the fourth magnet 15 include a hollow portion provided in the third focus coil 9c together with the first mounting piece 13a and the second mounting piece 13b of the second yoke 13, and a fourth focus coil 9d. It is comprised so that it may insertly arrange in the hollow part provided in.

  Reference numeral 16 denotes a fifth magnet that is bonded and fixed to a third mounting piece 10c formed on the first yoke 10, and includes a first focus coil 9a and a second focus coil 9b that are juxtaposed as shown. It arrange | positions on the outer side so that a connection part may correspond with the center of a magnet. Reference numeral 17 denotes a sixth magnet that is bonded and fixed to a third mounting piece 13c formed on the second yoke 13, and is provided with a third focus coil 9c and a fourth focus coil 9d that are juxtaposed as shown. It arrange | positions on the outer side so that a connection part may correspond with the center of a magnet.

  As described above, the objective lens driving device according to the present invention is configured, but the first focus coil 9a and the second focus coil 9b disposed on the side of the lens holder 5 where the first tracking coil 8a is provided. The first magnet 11, the second magnet 12, the fifth magnet 16 and the first yoke 10 are arranged on the opposite side of the lens holder 5, that is, on the side where the second tracking coil 8b is provided. 9c, the fourth focus coil 9d, the third magnet 14, the fourth magnet 15, the sixth magnet 17, and the second yoke 13, and a line with respect to a straight line A connecting the optical axes of the first objective lens 6 and the second objective lens 7. They are arranged symmetrically.

  In the present embodiment, the magnetization directions of the first magnet 11, the second magnet 12, the third magnet 14, the fourth magnet 15, the fifth magnet 16, and the sixth magnet 17 are as illustrated.

  In such a configuration, the magnetic flux generated from the first magnet 11 and the second magnet 12 is configured to act on the first tracking coil 8a, the first focus coil 9a, and the second focus coil 9b. The magnetic flux generated from the third magnet 14 and the fourth magnet 15 is configured to act on the second tracking coil 8b, the third focus coil 9c, and the fourth focus coil 9d.

  Therefore, if the winding direction of the first tracking coil 8a and the second tracking coil 8b is set so that the displacement force in the same direction works, the tracking holder 2 supplies the tracking drive current through the tracking wires 2a and 2b, so that the lens holder 5 can be moved in the tracking direction. Therefore, the tracking control operation in the optical pickup device can be performed.

  Further, if the winding directions of the first focus coil 9a, the second focus coil 9b, the third focus coil 9c, and the first focus coil 9d are set so that the displacement force in the same direction works, the focus drive current is changed to the focus wire 3a, Since the lens holder 5 can be displaced in the focus direction by supplying through 3b, the focus control operation in the optical pickup device can be performed.

Further, a radial tilt signal is supplied to the first focus coil 9a, the second focus coil 9b, the third focus coil 9c, and the first focus coil 9d through the tilt adjusting wires 4a and 4b, and is generated from each focus coil. By increasing or decreasing the displacement force, an operation of tilting the lens holder 5 in the radial direction, that is, a radial tilt adjustment operation can be performed.

  As described above, the tracking control operation, the focus control operation, and the radial tilt control operation are performed. In the present invention, the magnetic flux generated from the fifth magnet 16 acts on the first focus coil 9a and the second focus coil 9b. In addition, the magnetic flux generated from the sixth magnet 17 is configured to act on the third focus coil 9c and the fourth focus coil 9d.

  According to such a configuration, the force for displacing the lens holder 5 in the focus direction is increased by the magnetic flux generated from the fifth magnet 16 and the sixth magnet 17, and the braking force against the displacement operation of the lens holder 5. Therefore, an operation for suppressing unnecessary vibration, that is, an operation for preventing resonance can be performed.

  In the present embodiment, the case where the first objective lens 6 and the second objective lens 7 are arranged and fixed in the lens holder 5 has been described. However, the present invention is implemented in a lens holder in which one objective lens is arranged and fixed. Of course it is possible. Further, the lens holder 5 is configured to be supported by the six support wires. However, when the tilt adjustment is not necessary, the lens holder 5 can be configured to be supported by the four support wires.

It is a perspective view of the principal part which shows the objective lens drive device of this invention. It is a top view of the principal part which shows the objective lens drive device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed wiring board 5 Lens holder 6 1st objective lens 7 2nd objective lens 8a 1st tracking coil 8b 2nd tracking coil 9a 1st focus coil 9b 2nd focus coil 9c 3rd focus coil 9d 4th focus coil 11 1st Magnet 12 Second magnet 14 Third magnet 15 Fourth magnet 16 Fifth magnet 17 Sixth magnet

Claims (6)

The objective lens is fixed and supported by a plurality of support wires so that it can be displaced in the tracking direction, which is the radial direction of the optical disk, and in the focus direction, which is perpendicular to the signal surface of the optical disk, and is fixed to the housing or the like. An objective lens driving device including a tracking coil that generates a driving force in a tracking direction and a focusing direction by cooperating with a magnetic flux generated from a magnet and a lens holder on which the focusing coil is mounted. The first and second tracking coils are fixed on the side surface of the lens holder with the objective lens interposed therebetween, and the focus coil is arranged on the side surface side of the lens holder with the objective lens interposed therebetween. Winding hollow so as to have an axial winding axis And the third and fourth focus coils paired with the first and second focus coils arranged in parallel in the tracking direction, and the magnet includes the first, second, third and fourth magnets. In addition to the first, second, third and fourth magnets arranged in the hollow position of the focus coil, the outside of the first and second focus coils to generate magnetic flux acting on the first and second focus coils. And a sixth magnet disposed outside the third and fourth focus coils so as to generate a magnetic flux acting on the third and fourth focus coils. An objective lens driving device. 2. The objective lens driving device according to claim 1, wherein the tracking coil, the focus coil, and the magnet are arranged so as to be symmetrical with respect to a straight line connecting the optical axis center of the objective lens and the rotation center axis of the optical disk. . The first objective lens and the second objective lens for condensing laser beams of different wavelengths on signal recording layers provided on optical disks of different standards are incorporated in the lens holder. Objective lens drive. 4. The objective lens driving device according to claim 3, wherein the first objective lens and the second objective lens are arranged in a radial direction of the optical disc. 2. The objective lens driving device according to claim 1, wherein a radial tilt signal can be adjusted by superimposing and supplying a radial tilt signal to a focus driving current supplied to the focus coil. A pair of tracking wires for supplying a tracking drive current to the tracking coil, a pair of focus wires for supplying a focus drive current to the focus coil, and a pair of tilt adjusting wires for supplying a radial tilt signal superimposed on the focus coil 6. The objective lens driving device according to claim 5, wherein the lens holder is supported so as to be displaceable.

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