JP2011003229A - Objective lens actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens actuator which can cope with an adjustment error and disturbance originating from component accuracy and assembling accuracy and can perform minute adjustment.SOLUTION: In the objective lens actuator of an optical pickup device, which includes a base 1, a lens holder 2 supported to be freely displaced to the base and made of a non-magnetic body and an objective lens 4 attached to the lens holder and wherein a coil part having at least a focus coil and a tracking coil is provided at the lens holder 2, a magnetic field generating part 3 applying a magnetic field to the coil part is provided on the base side, the objective lens is moved to a prescribed position by an electromagnetic action of the coil part and the magnetic field generating part and an optical disk is irradiated with a laser beam to perform recording and reproducing of data, the magnetic field generating part 3 is constituted of variable magnetic field generating parts 31 and 32 using coils.

Description

  The present invention relates to an objective lens actuator of an optical pickup device that records or reproduces data by irradiating an optical disc with laser light.

  Conventionally, many types of optical discs such as CD (compact disc), DVD (digital versatile disc), HD-DVD (high density DVD), and Blu-ray disc have been put to practical use as disk-shaped storage media. In such many types of optical discs, the wavelength of the laser beam to be used, the depth of the transparent layer to the recording surface, etc. are different, so that a single objective lens is used to support a plurality of types of optical discs. There is. Further, in order to accurately irradiate the recording surface formed on the disk with laser light, correction is performed to displace the optical spot in the focus direction and the tracking direction.

  Such correction in the focus direction is focusing adjustment, and correction in the tracking direction is tracking adjustment. These focusing adjustment and tracking adjustment are performed via an objective lens driving device (objective lens actuator). The focus direction is a direction parallel to the optical axis direction of the objective lens, and the tracking direction is a direction parallel to the radial direction of the optical disc.

  An example of a conventional objective lens actuator will be described with reference to FIG.

  As shown in the schematic perspective view of the overall configuration shown in FIG. 3 (a) and the exploded perspective view of FIG. 3 (b), the conventional objective lens actuator TA1 emits light at the center of the base 1 made of a metal having ferromagnetism. A through hole 1a through which the beam passes is formed, and a resin lens holder 2 that supports the objective lens 4 is disposed above the through hole 1a. In addition, the base 1 is provided with a pair of permanent magnets 3a and 3b as magnetic field generating members arranged to face each other with a predetermined interval so as to sandwich the lens holder 2. The permanent magnets 3 a and 3 b are magnetically attached to yokes 1 b and 1 c whose outer surfaces are bent from the base 1.

  An optical path hole is formed in the lens holder 2 so that the light beam can pass therethrough. An objective lens holding portion 2a for holding the objective lens 4 is formed on the upper side of the optical path hole. A focus coil 5 is provided on the inner side wall of the lens holder 2 so as to surround the optical axis of the objective lens 4 held by the lens holder 2, and is fixed to the lens holder 2 with an adhesive or the like.

  In addition, tracking coils 6a and 6b and tracking coils 6c and 6d are provided on the outside of the side walls of the lens holder 2 on both side walls facing the permanent magnets 3a and 3b so as to be lined up in pairs. Further, the tracking coil 6a and the tracking coil 6c, and the tracking coil 6b and the tracking coil 6d are respectively arranged at symmetrical positions. The tracking coils 6a to 6d are fixed to the lens holder 2 with an adhesive or the like. The four tracking coils 6a to 6d are connected by a single line as a whole.

  On the base 1, a gel box 7 made of a resin molded product such as polycarbonate is fixed to the outer surface side of a yoke 1c on which one permanent magnet (for example, permanent magnet 3b) is magnetically attached. A circuit board 8 is erected on the base 1 adjacent to the outside of the gel box 7.

  On this circuit board 8, one end of each of the conductive wires 9a, 9b, 9c, 9d, 9e, and 9f is connected by soldering on the left and right sides, respectively, in plural, for example, three places. Yes. The wires 9a to 9c and the wires 9d to 9f are inserted through insertion holes 10a and 10b formed in the gel box 7, respectively.

  The other ends of the wires 9a to 9c are fixed to the relay substrate 11a provided on the side wall of the lens holder 2 by soldering. The other ends of the wires 9d to 9f are fixed to the relay substrate 11b provided on the side wall of the lens holder 2 by soldering. As a result, the lens holder 2 is supported by the wires 9 a to 9 f so as to be swingable with respect to the base 1.

  Note that a wiring pattern is formed on the relay boards 11a and 11b, and the wires 9a and 9d are electrically connected to the focus coil 5 via the relay boards 11a and 11b. Further, the wire 9c and the wire 9f are electrically connected to the tracking coils 6a to 6d via the relay boards 11a and 11b.

  The insertion holes 10a and 10b of the gel box 7 are filled with a gel material mainly composed of silicon. Here, the gel material is obtained by injecting a low-viscosity gel material (sol form) into the insertion holes 10a and 10b of the gel box 7 and then curing the gel material by ultraviolet irradiation for a predetermined time.

  The operation of the objective lens actuator TA1 configured as described above will be briefly described. When a current is supplied from the circuit board 8 to the focus coil 5 through the wires 9a and 9d, the lens holder 2 can be displaced in the focus direction by an electromagnetic action with a magnetic field formed by the permanent magnets 3a and 3b. For this reason, the focusing adjustment can be performed by adjusting the magnitude and direction of the current supplied to the focus coil 5.

  Further, when a current is supplied from the circuit board 8 to the tracking coils 6a to 6d through the wires 9c and 9f, the lens holder 2 is moved in the tracking direction by an electromagnetic action with a magnetic field formed by the permanent magnets 3a and 3b. Displaceable. For this reason, tracking adjustment becomes possible by adjusting the magnitude | size and direction of the electric current supplied to tracking coil 6a-6d.

  The conventional objective lens actuator TA1 is configured as described above. Next, frequency characteristics of such a wire support type objective lens actuator will be described. The objective lens actuator TA1 has a very large response displacement at the primary resonance frequency. However, if this overshoot amount is too large, inconvenience occurs. For this reason, in the conventional objective lens actuator TA1, the gel box 7 is filled with a gel material (attenuating material) to reduce the amount of overshoot (suppress primary resonance).

  Further, there is a portion where the response displacement is disturbed at a frequency higher than the primary resonance frequency. This is due to the occurrence of pitching resonance and yawing resonance due to vibration in the longitudinal direction of the wire. The pitching resonance is a resonance mode that occurs in the direction around the axis parallel to the tracking direction. Yawing resonance is a resonance mode that occurs in a direction around an axis parallel to the focus direction.

  In order to accurately position the optical spot at the recording portion of the optical disk, it is important to adjust the inclination of the so-called objective lens that suppresses these resonance modes. For this purpose, in addition to the focus coil and the tracking coil, a tilt coil is provided, and an objective lens driving device for an optical pickup (for example, see Patent Document 1) that controls the posture of the tilt coil via a permanent magnet, and four permanent magnets An objective lens driving device that includes a focus coil and a tracking coil and drives the lens holder in a focusing direction, a radial tilt direction, and a tangential tilt direction by switching the direction of current flowing in each coil (for example, Patent Document 2) Have already been filed.

JP 2002-92916 A JP 2000-195078 A

  It is possible to adjust the displacement of the lens holder, that is, the position and inclination of the objective lens by the electromagnetic action of a coil such as a focus coil, tracking coil or tilt coil and a magnetic field formed by a permanent magnet. By adjusting the magnitude and direction of the current supplied to each coil such as a coil or a tracking coil, focusing adjustment, tracking adjustment, and inclination adjustment can be performed.

  However, in the method of adjusting the displacement of the lens holder using the electromagnetic action of a permanent magnet and a coil that exhibits a predetermined magnetic field, subtle adjustment errors and disturbances derived from the accuracy of parts and assembly accuracy that make up each part. May occur. For this reason, it is difficult to perform detailed control that requires more precise fine adjustment only by the electromagnetic action of the permanent magnet and coil that exhibits a predetermined magnetic field, and it is not possible to further improve the driving performance. This causes a problem.

  For this purpose, an objective lens actuator that can cope with subtle adjustment errors and disturbances derived from the accuracy of components and the assembly accuracy is required.

  In view of the above problems, an object of the present invention is to provide an objective lens actuator that can cope with adjustment errors and disturbances derived from component accuracy and assembly accuracy and enables fine adjustment.

  To achieve the above object, the present invention provides a base, a lens holder made of a non-magnetic material that holds the objective lens and is supported to be displaceable with respect to the base, and at least a focus coil and a tracking coil fixed to the lens holder. And a magnetic field generation unit that stands upright on the base and is opposed to the lens holder and applies a magnetic field to the coil unit, and by an electromagnetic force action between the coil unit and the magnetic field generation unit. In the objective lens actuator that moves the objective lens to a predetermined position, the magnetic field generator is a variable magnetic field generator using a coil.

  According to this configuration, since the magnetic field applied to the focus coil and tracking coil of the lens holder that is the displacement portion can be changed, the objective lens actuator that can further finely adjust the focusing direction and the tracking direction displacement of the objective lens, Become.

  According to the present invention, in the objective lens actuator having the above-described configuration, the variable magnetic field generator is erected from the base, and a coil is fixed to each of a pair of yokes disposed so as to sandwich the lens holder. It is characterized by that. According to this configuration, since the lens holder is disposed between the pair of variable magnetic field generators in which the coil is fixed to the yoke, a magnetic field can be stably applied to each coil mounted on the lens holder. In addition, the displacement of the lens holder can be adjusted by changing the strength of the magnetic field to be applied.

  Further, according to the present invention, in the objective lens actuator configured as described above, the magnetic field generator generates a predetermined basic magnetic field, and the position of the objective lens is not in a desired position in a state where the basic magnetic field is applied. Sometimes, the magnetic field control is performed by changing the applied magnetic field. According to this configuration, control is normally performed because a constant magnetic field is generated and the magnetic field is changed as necessary. Further, since it is possible to cope with subtle positional deviations of the objective lens, it is possible to cope with adjustment errors and disturbances derived from component accuracy and assembly accuracy, and precise fine adjustment is possible.

  In the objective lens actuator configured as described above, the present invention is characterized in that the coil section further includes a tilt coil for adjusting the tilt of the lens holder. According to this configuration, since the tilt of the objective lens can be finely adjusted in addition to the focusing adjustment and the tracking adjustment, the adjustable region is expanded and the objective lens actuator having a sufficient adjustment range is obtained.

  According to the present invention, in an objective lens actuator of an optical pickup device that records or reproduces data by irradiating an optical disk with laser light, magnetic field generation is performed by applying a magnetic field to a coil portion having a focus coil and a tracking coil provided in a lens holder. Since the variable magnetic field generator using a coil is used, the magnetic field applied to the focus coil and tracking coil of the lens holder, which is the displacement unit, can be changed, and the displacement of the focusing direction and tracking direction of the objective lens It is possible to obtain an objective lens actuator that can be further finely adjusted.

It is a schematic perspective view which shows the principal part structure of the objective lens actuator which concerns on this invention. The whole structure of an example of the objective lens actuator which concerns on this invention is shown, (a) is a schematic perspective view of a whole structure, (b) is a schematic side view. The whole structure of an example of the conventional objective lens actuator is shown, (a) is a schematic perspective view of a whole structure, (b) is a disassembled perspective view.

  Embodiments of the present invention will be described below with reference to the drawings. Moreover, the same code | symbol is used about the same structural member, and detailed description is abbreviate | omitted suitably.

  The objective lens actuator TA of the present embodiment is a drive device that displaces the objective lens 4 used in an optical pickup device that records or reproduces data by irradiating a laser beam on an optical disk, as shown in FIG. A base 1 made of a metal having ferromagnetism, a lens holder 2 made of a non-magnetic material and supported movably with respect to the base 1, and an objective lens 4 attached to the lens holder 2 are provided.

  Further, the actuator is a wire support type that is swingably supported via a plurality of conductive wires, and at least a focus coil 5 and a tracking coil 6 (6a to 6d) are provided on the lens holder 2 side that is a movable part. The magnetic field generator 3 (31, 32) for applying a magnetic field to the coil is provided on the base 1 side serving as a fixed part. Therefore, by applying electric power of a predetermined voltage to the coil unit, the objective lens 4 can be displaced by a predetermined amount by the electromagnetic force action between the coil unit and the magnetic field generator 3 (31, 32).

  In the present embodiment, the magnetic field generator 3 is the variable magnetic field generators 31 and 32 using coils. Since the magnetic field generator 3 (31, 32) applies a magnetic field to the coil portions such as the focus coil 5 and the tracking coils 6 (6a to 6d), by adjusting the magnitude and direction of the current supplied to each coil. Focusing adjustment, tracking adjustment and tilt adjustment can be performed.

  At this time, if the magnetic field generating unit 3 is a permanent magnet, the magnetic field applied to the coil unit is constant, so that focusing adjustment, tracking adjustment, and tilt adjustment are within the adjustment range of the magnitude of the current supplied to each coil. It can be performed. However, subtle adjustment errors and disturbances may occur due to the accuracy and assembly accuracy of the parts that make up each part. It is difficult to perform detailed control that requires adjustment.

  Therefore, as in the present embodiment, if the magnetic field generator 3 is the variable magnetic field generator 31 or 32 using a coil, the magnitude of the magnetic field applied to the focus coil 5 and the tracking coil 6 of the lens holder 2 that is the displacement unit. Therefore, the displacement of the objective lens in the focusing direction and the tracking direction can be further increased and fine adjustment can be performed.

  For example, the variable magnetic field generator 31 made of a coil is fixed to the yoke 1b by bonding or the like, and the variable magnetic field generator 32 made of a coil is fixed to the yoke 1c by bonding or the like, and a current of a predetermined magnitude is applied to each coil. By supplying, a predetermined magnetic field can be applied to the focus coil 5 and the tracking coil 6. Moreover, it is good also as a structure which raises a magnetic flux density further as a yoke shape provided with the iron core-like part which winds each coil.

  Since the magnetic field generators for applying a magnetic field to each coil unit such as the focus coil 5 and the tracking coil 6 are the variable magnetic field generators 31 and 32 made of coils, a basic magnetic field defined in advance in the variable magnetic field generators 31 and 32 is used. By supplying a current to be generated, the variable magnetic field generators 31 and 32 generate a basic magnetic field defined in advance. Further, when the position of the objective lens 4 is not in a desired position with the basic magnetic field applied, the current to be supplied is adjusted, and the magnitude of the magnetic field applied to the focus coil 5 and the tracking coil 6 is adjusted. The magnetic field can be controlled. With this configuration, control is normally performed because a magnetic field having a constant magnitude is generated and the magnitude of the magnetic field is adjusted as necessary. Further, since it is possible to cope with subtle positional deviations of the objective lens 4, it is possible to cope with adjustment errors and disturbances derived from component accuracy and assembly accuracy, and precise fine adjustment is possible.

  As described above, if the magnetic field generator 3 is an electromagnet type variable magnetic field generator 31 or 32 using a coil, it is possible to cope with adjustment errors and disturbances derived from component accuracy and assembly accuracy, and precise fine adjustment is possible. A possible objective lens actuator TA is preferred. For this reason, it is possible to suppress the development burden for the accuracy tracking.

  Next, the overall configuration of the objective lens actuator TA will be described in more detail with reference to FIG.

  The objective lens actuator TA of the present embodiment may be the same as the conventional objective lens actuator TA1 shown in FIG. 3 except that the magnetic field generator 3 is variable magnetic field generators 31 and 32 using coils. Therefore, the same components are described with the same reference numerals. Further, the present invention may be configured to use an attenuation material that suppresses resonance that occurs in the high frequency region, and is an objective lens actuator TA that includes an attenuation material that suppresses resonance that occurs in the high frequency region caused by the elastic wires 9a to 9f. The form will be described below.

  As shown in FIG. 2A, the objective lens actuator TA according to the present embodiment transmits a light beam to the central portion of the base 1 made of a ferromagnetic metal, like the conventional objective lens actuator TA1 described above. A through hole 1a (see FIG. 3B) is formed, and a lens holder 2 that supports the objective lens 4 is disposed above the through hole 1a.

  The lens holder 2 is supported in a swingable manner with respect to the base 1 by wires 9a to 9f (see FIG. 3B) made of an electrically conductive material having elasticity, and the focus coil 5 and the tracking coil. 6 (6a to 6d) is assembled. The other ends of the wires 9a to 9c are fixed to the relay substrate 13a provided on the side wall of the lens holder 2 by soldering, and the other ends of the wires 9d to 9f are connected to the relay substrate 13b provided on the side wall of the lens holder 2. It is fixed by soldering.

  Reference numerals 15 a and 15 b denote damping material holding portions, each of which fills the cavity portions 16 a and 16 b of the substantially U-shaped frame projecting from the side wall portion of the lens holder 2 with the damping material 18. In addition, the slits 14 are provided in the relay boards 13a and 13b so that the resonance caused by the elastic wires 9a to 9f is effectively suppressed for each wire.

  Further, each insertion hole 10a, 10b of the gel box 7 is filled with a gel material mainly composed of silicon, and the wires 9a to 9f are connected to the circuit board 8 disposed outside the gel box 7. ing.

  For example, as shown in FIG. 2B, by filling the damping material 17 made of a gel material, the response displacement that increases at the primary resonance frequency when the lens holder 2 is driven is suppressed (the primary resonance is suppressed). )be able to. Further, by adopting a configuration including the relay boards 13a and 13b having the slits 14 and the damping material holding portions 15a and 15b filled with the damping material 18, the pitching resonance generated in the high frequency region having a frequency higher than the primary resonance frequency can be obtained. Yawing resonance can be effectively suppressed.

  The focus coil 5 is wound on the inner side wall of the lens holder 2 in a substantially rectangular shape so as to surround the optical axis of the objective lens 4 held by the lens holder 2, and is fixed with an adhesive or the like. The tracking coils 6 (6a to 6d) are wound in a substantially rectangular shape, and are separated on the left and right sides of the side walls of the two lens holders 2 facing the magnetic field generator 3 (31, 32). The tracking coils 6a and 6c and the tracking coils 6b and 6d are arranged at positions facing each other with the lens holder 2 interposed therebetween, and are fixed with an adhesive or the like. These four tracking coils 6 (6a to 6d) are connected by a single line as a whole. Further, current is supplied to the focus coil 5 and the tracking coils 6 (6a to 6d) from the circuit board 8 through the relay boards 13a and 13b.

  Here, as the magnetic field generation unit 3, variable magnetic field generation units 31 and 32 using coils are used, and for example, magnetic fields are generated in opposite directions on the yokes 1b and 1c bent from the base 1. It is set as the structure which attaches the coil wound by the shape (for example, adheres and fixes). Each coil is connected to the circuit board 8 and supplied with a predetermined current.

  Since the base 1 has ferromagnetism, the yokes 1b and 1c bent from the base 1 also have ferromagnetism. That is, the variable magnetic field generators 31 and 32 are configured such that the coils are bonded and fixed to a pair of ferromagnetic yokes that are erected from the base 1 and are opposed to each other so as to sandwich the lens holder.

  With the above configuration, each of the yokes 1b and 1c stabilizes the magnetic flux to have a high density, and the focus coil 5 and the tracking coil 6 (6a to 6d) disposed between the variable magnetic field generation units 31 and 32 facing each other. By applying a magnetic flux, an electromagnetic force corresponding to the current supplied to each coil can be applied. Further, by this, the lens holder 2 can be displaced in the focus direction by the electromagnetic force action corresponding to the current supplied to the focus coil 5, and the electromagnetic force corresponding to the current supplied to the tracking coil 6 (6a to 6d). Due to the action, it can be displaced in the tracking direction.

  Further, a current for generating a predetermined basic magnetic field is supplied to the magnetic field generator 3 (31, 32) so that a basic electromagnetic force is applied to the focus coil 5 and the tracking coil 6 (6a to 6d). Yes.

  The state in which this basic magnetic field is generated is equivalent to the state in which a conventional permanent magnet is interposed, and this state is maintained, and each of the focus coil 5 and the tracking coil 6 (6a to 6d) is maintained. The position of the objective lens 4 is adjusted by controlling the current supplied to the coil.

  However, a state in which the objective lens 4 does not reach the desired position due to adjustment errors and disturbances derived from the component accuracy and assembly accuracy of each component constituting the objective lens actuator TA, that is, the adjustment region becomes insufficient. There is. In this case, it is possible to adjust the strength of the magnetic field applied to the focus coil 5 and the tracking coil 6 (6a to 6d) by changing the current supplied to the magnetic field generator 3 (31, 32).

  If it is said structure, it will become possible to adjust the displacement amount of the lens holder 2 by changing the strength of the magnetic field applied to the focus coil 5 and the tracking coil 6 (6a-6d), and the adjustment area | region of the objective lens 4 will be adjusted. Since it becomes large, it is preferable. In addition, a simple control that usually generates a constant basic magnetic field and changes the magnetic field as needed, can handle adjustment errors and disturbances resulting from component accuracy and assembly accuracy, and allows precise fine adjustment. This is preferable because it is possible to cope with a slight positional deviation of the objective lens.

  Further, when a tilt coil (not shown) for adjusting the tilt of the lens holder 2 is provided in addition to the focus coil 5 and the tracking coil 6 (6a to 6d), the tilt of the objective lens in addition to the focusing adjustment and the tracking adjustment. Can be finely adjusted, and the adjustable region is further expanded, so that an objective lens actuator having a further margin in the adjustment range of the objective lens is preferable.

  As described above, the objective lens actuator in which the variable magnetic field generation unit is mounted on the wire support type that is supported by using a plurality of wires has been described. However, the variable magnetic field generation unit according to the present invention is an axial sliding type objective lens actuator. You may attach to. Even with a shaft-sliding objective lens actuator, the variable magnetic field generator can be used to increase the adjustment area of the objective lens, and to cope with adjustment errors and disturbances caused by component accuracy and assembly accuracy. It becomes.

  As described above, according to the objective lens actuator according to the present invention, in the objective lens actuator of the optical pickup device that moves the objective lens by the electromagnetic force action of the coil portion provided on the lens holder side and the magnetic field generation portion provided on the base side. Since the magnetic field generation unit is a variable magnetic field generation unit using a coil, the magnetic field applied to the focus coil and tracking coil of the lens holder, which is the displacement unit, can be changed, and the focusing direction and tracking of the objective lens can be changed. An objective lens actuator that can further finely adjust the displacement in the direction can be obtained.

  Further, the magnetic field generation unit generates a predetermined basic magnetic field, and changes the magnetic field to be applied when the position of the objective lens is not in a desired position in a state where the basic magnetic field is applied. By controlling, it is a simple control that usually generates a constant basic magnetic field and changes the magnetic field as necessary, and can handle adjustment errors and disturbances caused by component accuracy and assembly accuracy. Fine adjustment is possible, and it is possible to cope with subtle displacement of the objective lens. Thus, according to the present invention, the adjustment area of the objective lens is preferably increased.

  For this reason, the objective lens actuator according to the present invention has a large adjustment area of the objective lens, and can stably operate the objective lens without increasing the component accuracy and the assembly accuracy. Can be suitably applied to an objective lens actuator of an optical pickup device that records or reproduces data in correspondence with a plurality of types of optical discs.

DESCRIPTION OF SYMBOLS 1 Base 2 Lens holder 3 Magnetic field generation part 31 Variable magnetic field generation part 32 Variable magnetic field generation part 4 Objective lens 5 Focus coil 6 Tracking coil TA Objective lens actuator (according to this invention)
TA1 Objective lens actuator (conventional)

Claims (4)

A base, a lens holder made of a non-magnetic material that holds the objective lens and is supported to be displaceable with respect to the base; a coil portion fixed to the lens holder and having at least a focus coil and a tracking coil; and standing on the base An objective lens that is disposed opposite to the lens holder and applies a magnetic field to the coil portion, and moves the objective lens to a predetermined position by an electromagnetic force action between the coil portion and the magnetic field generator. In the actuator
An objective lens actuator, wherein the magnetic field generator is a variable magnetic field generator using a coil.   2. The objective according to claim 1, wherein the variable magnetic field generation unit is configured such that a coil is bonded and fixed to a pair of yokes that are erected from the base and are opposed to each other so as to sandwich the lens holder. Lens actuator.   The variable magnetic field generator generates a basic magnetic field defined in advance, and controls the magnetic field by changing the applied magnetic field when the position of the objective lens is not in a desired position with the basic magnetic field applied. The objective lens actuator according to claim 1, wherein the objective lens actuator is provided.   The objective lens actuator according to claim 1, wherein the coil unit further includes a tilt coil that adjusts the tilt of the lens holder.

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