JP5067054B2 - Objective lens drive - Google Patents

Description

  The present invention relates to an objective lens driving apparatus that irradiates a laser beam focused on an optical disk in a spot shape on an optical disk while controlling the objective lens in a focus direction and a tracking direction with respect to the optical disk. The present invention relates to an optical pickup apparatus configured to attenuate high-order resonance and lower the Q value during focus servo.

  In general, an optical recording medium (hereinafter referred to as an optical disk) is used to transmit information signals such as video information, audio information, and computer data on a spiral (or concentric) track on a signal surface formed on an optical disk substrate. It is frequently used because a desired track can be accessed at a high speed when recording a density and reproducing a recorded track.

  In addition to CDs (Compact Discs) and DVDs (Digital Versatile Discs), BDs (Blu-ray Discs) that can record or reproduce information signals at a higher density than DVDs have recently appeared on this type of optical discs. In this type of optical disk, an objective lens is held in a lens holder that is swingably supported via a plurality of suspension wires in an objective lens driving device, and a laser beam emitted from a semiconductor laser by the objective lens. A laser beam obtained by squeezing light is irradiated onto a signal surface of an optical disc in a spot shape to be recorded or reproduced.

  The above-described structural form of the objective lens driving device is generally configured such that each end of a plurality of suspension wires is fixed to a fixing portion in which a wire support block is fixed on a base and a lens holder that holds the objective lens, and A movable portion that swings in a state where the other ends of the suspension wires are supported by the wire support block, and an objective lens held by the lens holder on the signal surface of the optical recording medium via the suspension wires. On the other hand, magnetic circuit means for swinging in the focus direction and the tracking direction is provided.

  At this time, the magnetic circuit means described above can be broadly classified into a moving coil method (MC method) and a moving magnet method (MM method).

  First, in the magnetic circuit means to which the moving coil method (MC method) is applied, the magnet is fixed to the base on the fixed part side, and the focus coil and the tracking coil are fixed to the lens holder on the movable part side.

  In the objective lens driving device to which this moving coil system (MC system) magnetic circuit means is applied, although the wiring process to the focus coil and the track king coil fixed to the lens holder on the movable part side is relatively troublesome, the lens holder Therefore, the followability of the focus servo and track king servo to the optical disk can be improved.

  On the other hand, in the magnetic circuit means using the moving magnet method (MM method), the focus coil and the tracking coil are fixed to the base on the fixed portion side, and the magnet is fixed to the lens holder on the movable portion side.

  In the objective lens driving device to which the magnetic circuit means by the moving magnet method (MM method) is applied, the focus coil and the track king coil are fixed to the base on the fixed portion side, so that the wiring process is easy and there is a risk of disconnection. There is a merit that there is no.

  Further, since a heavy magnet is fixed to the lens holder on the movable part side, there are advantages that the rigidity on the movable part side is high and demerits that the movable part side is heavy.

  By the way, in an objective lens driving device that employs either the moving coil method (MC method) or the moving magnet method (MM method), the laser beam emitted from the objective lens is applied to the track on the signal surface of the optical disk substrate. The servo follows the focus direction and tracking direction, but if resonance occurs during servo, there is a possibility that the servo will be adversely affected. .

  At this time, it is also a well-known fact that the higher-order resonance frequency and Q value are determined by the rigidity of the movable portion, and that the resonance mode of the higher-order resonance is generated by bending or twisting of the movable portion. Further, if the frequency of high-order resonance is low, the gain margin is reduced even if the Q value has the same peak due to the Bode diagram gain curve, which is disadvantageous for the servo. Similarly, even if the higher order resonance frequency can be increased, if the Q value increases, it is also disadvantageous for the servo.

  Therefore, conventionally, a resin material is usually used as the material of the movable part in order to reduce the weight. However, when the hardness of the resin material is increased, the higher order resonance frequency is increased and the Q value is increased. If a material with a large internal loss was used to reduce the gain, the gain margin could not be improved, although the higher order resonance frequency decreased.

  In recent years, there has been a demand from the market to reduce the thickness of the objective lens driving device itself, and in order to satisfy this requirement, the thickness of the movable part must be reduced. Resonance countermeasures are becoming more difficult.

  As an example of a conventional example for dealing with resonance in the objective lens driving device described above, even if the frequency of the electromagnetic driving mechanism is higher than the servo band and the lens holder resonates, the lens aberration is reduced to improve the quality of the pickup device. There is an actuator for a pickup device that can be used (for example, see Patent Document 1).

  In the actuator for a pickup device disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-164696), the lens holder resonates between the outer peripheral edge of the objective lens and the lens holder, although illustration is omitted here. The adhesive layer has a thickness sufficient to absorb the bending even if it is bent.

  As a result, even when the frequency at which the electromagnetic drive mechanism operates becomes higher than the servo band and the lens holder resonates, the adhesive layer has a buffer function, so that the deflection of the lens holder is less transmitted to the objective lens. .

  Therefore, it is described that the objective lens is hardly deformed, the lens aberration is reduced, and the quality of the pickup device can be improved.

  Further, as another example of the conventional example for dealing with resonance in the objective lens driving device described above, an optical head device capable of removing the influence of mechanical vibration generated at a higher-order (secondary or higher) resonance frequency and optical recording using the same There is a playback device (see, for example, Patent Document 2).

  In the optical head device disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2007-18601) and an optical recording / reproducing device using the same, the trapezoidal outline of the trapezoidal shape of the lens holding portion is omitted here. A damping system in which a pair of weights formed in a metallic thin plate shape is bonded to each side wall formed at a predetermined angle from both sides of the side wall forming the upper bottom using a viscoelastic adhesive is attached.

  As a result, a viscous damping characteristic that attenuates the vibration in the focus direction (optical axis direction) of the objective lens is obtained, and it is described that the influence of mechanical vibration generated at a higher-order (second-order or higher) resonance frequency can be removed. ing.

JP 2004-164696 A JP 2007-18601 A

  By the way, according to the actuator for a pickup device disclosed in Patent Document 1 described above, the adhesive layer formed between the outer peripheral edge portion of the objective lens and the lens holder absorbs bending when the lens holder resonates. Although the above-described adhesive layer has a function of preventing the deflection from being transmitted to the objective lens, the above-described adhesive layer does not attenuate the higher-order resonance generated during focus servo to the objective lens and lower the Q value.

  On the other hand, according to the optical head device disclosed in Patent Document 2 described above and the optical recording / reproducing device using the same, a pair of metal thin plates formed on both side walls of the trapezoidal outline of the trapezoidal shape of the lens holding portion. Although a damping system that attaches the weight of the lens to the objective lens using a viscoelastic adhesive is attached, the influence of mechanical vibration that occurs at higher-order (secondary or higher) resonance frequency during focus servo to the objective lens can be eliminated, but the market May cause quality problems, such as the weight coming off, and not only the assembly workability will be lowered due to the weight being attached, but also the weight of the weight will be required to some extent to lower the Q value of higher order resonance. Accordingly, the weight of the movable part increases accordingly, and there is a problem that the focus drive sensitivity and the tracking drive sensitivity are lowered.

  Therefore, an objective lens driving device having a simple structure that can attenuate high-order resonance and lower the Q value during focus servo to the objective lens is desired.

This invention is made | formed in view of the said subject, 1st invention is the fixing | fixed part which has a wire support block,
Comprising a lens holder having an objective lens holder on which an objective lens is held the objective lens holding portion is a frame-shaped portion connected to one end of the plurality of suspension wires to the frame-like portion is fixed respectively, said plurality a movable part which is swingable with respect to the fixed part the other end of the suspension wires is respectively supported on the wire support block,
Magnetic drive means (magnetic circuit means) for swinging the movable part in the focus direction and the tracking direction with respect to the signal surface of the optical recording medium via the plurality of suspension wires ,
An adhesive having a characteristic of absorbing vibrations in the vicinity of the high-order resonance frequency generated in the movable part during focus servo is fixed to a position in the vicinity of the objective lens in the objective lens holding part. An objective lens driving device.
According to a second aspect of the present invention, in the objective lens driving device according to the first aspect, the adhesive is fixed to a position on the opposite side of the frame-shaped portion across the center of gravity of the movable portion. The objective lens drive device characterized by the above.

Further, a third invention is the objective lens driving device according to the first invention or the second invention described above,
The magnetic drive means (magnetic circuit means) is characterized in that a magnet is fixed to the fixed portion, and a focus coil and a tracking coil are fixed to the frame-shaped portion of the lens holder. It is.

According to a fourth aspect of the present invention, there is provided the objective lens driving device according to the first aspect or the second aspect of the present invention .
The magnetic drive means (magnetic circuit means) is characterized in that a focus coil and a tracking coil are fixed to the fixed portion, and a magnet is fixed to the frame-shaped portion of the lens holder. It is.

Furthermore, a fifth aspect of the invention is the objective lens driving device according to any one of the first to fourth aspects of the invention described above.
The objective lens driving device is characterized in that the application amount of the adhesive is set within a range of 0.25% to 1.75% with respect to the weight of the movable part.

  According to the objective lens driving device according to the present invention, a plurality of suspension wires are suspended between the lens holder holding the objective lens and the wire support block on the fixed part side, and held on the lens holder on the movable part side. When the objective lens is swung in the focus direction and the tracking direction with respect to the signal surface of the optical recording medium by the magnetic circuit means via the suspension wire, one end side of the lens holder and the other side with the center of gravity position of the movable part interposed therebetween Since an adhesive having a characteristic of absorbing vibrations in the vicinity of the higher order resonance frequency generated in the movable part during focus servo is fixed to at least one of the end side, the Q value is obtained by damping the higher order resonance generated during the focus servo. And the temperature characteristics against the GAIN margin of higher order resonance can be maintained well. Quality and reliability with vibration countermeasures structure is easy to be able to provide a good objective lens driving device.

  At this time, in the objective lens driving device according to the present invention, one of the magnetic circuit means of the moving coil method (MC method) or the moving magnet method (MM method) may be applied.

  Furthermore, by setting the application amount of the adhesive within the range of 0.25% to 1.75% with respect to the weight of the movable part, a high-order resonance frequency generated in the movable part at the time of focus servo. The nearby vibration can be damped well.

  Hereinafter, an embodiment of the objective lens driving device according to the present invention will be described in detail in the order of Embodiment 1 to Embodiment 3 with reference to FIGS.

  In Examples 1 to 3 below, the X-axis is a straight line that is orthogonal to the optical axis of the objective lens, passes through the center of the base and the lens holder in the width direction, and is substantially parallel to the suspension direction of the suspension wire. In the following description, the axis is a straight line that is orthogonal to the optical axis of the objective lens and orthogonal to the X axis, and the Z axis is a straight line that substantially matches the optical axis of the objective lens.

FIG. 1 is a perspective view showing an objective lens driving device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing frequency characteristics of a rubber-based adhesive used in the objective lens driving device of Example 1 according to the present invention.
FIG. 3 is a frequency characteristic diagram for explaining the focus servo characteristics in the objective lens driving apparatus according to the first embodiment of the present invention. FIG. 3A is a comparative example in which a rubber-based adhesive is attached to the objective lens holding portion of the lens holder. The case where the agent is not applied is shown, (b) is a diagram showing a case where a rubber adhesive is applied to the objective lens holding portion of the lens holder as Example 1,
FIG. 4 is a characteristic diagram for explaining the GAIN margin and frequency change of higher-order resonance due to temperature in the objective lens driving device of Example 1 according to the present invention. As a comparative example, the objective lens holding unit of the lens holder is shown in FIG. 2 is a diagram showing a case where a rubber adhesive is not applied, as a solid line, and a case where a rubber adhesive is applied to an objective lens holding portion of a lens holder as Example 1 as a dotted line. FIG.

  As shown in FIG. 1, the objective lens driving apparatus 10A according to the first embodiment of the present invention applies a moving coil system (MC system) magnetic circuit means to swing a fixed part and above the fixed part. And a movable part.

  In the objective lens driving device 10A according to the first embodiment of the present invention described above, first, the fixed portion side will be described. A base 11 serving as a base of the device 10A is formed by bending using an iron material or a soft magnetic material. Yes.

  An objective lens holding portion 16a side of a lens holder 16 (to be described later) on the base 11 will be referred to as a front side, and a frame-like portion 16b side of the lens holder 16 will be referred to as a rear side. A pair of upright pieces 11b and 11c are formed at the front part and the middle part of the upper surface 11a by cutting upward and facing each other at a distance substantially parallel to the Y axis perpendicular to the X axis. In addition, a pair of magnets 12 and 13 are fixed to the pair of upright pieces 11b and 11c so as to face each other inwardly, and in a square hole 16b1 formed in a frame-like portion 16b of the lens holder 16 described later. It faces.

  In addition, a wire support block 14 formed using a resin material is fixed on the upper surface 11a of the base 11 behind a frame-shaped portion 16b of a lens holder 16 described later, using an adhesive (not shown). The wiring board 15 is fixed to the back surface of the wire support block 14.

  From the above, the fixing portion is composed of the base 11, the pair of magnets 12 and 13 fixed to the pair of standing pieces 11 b and 11 c of the base 11, the wire support block 14, and the wiring board 15.

  Next, the movable part side will be described. In the lens holder 16, the objective lens holding part 16a and the frame-like part 16b are integrally formed using a resin material.

  At this time, the objective lens holding portion 16a of the lens holder 16 is formed on the left side (one end side) in the X-axis direction with a reduced thickness in the height direction. A stepped round hole 16a1 is formed through the inside, and the objective lens 17 is fixedly held in the stepped round hole 16a1 using an adhesive (not shown).

  The frame-shaped portion 16b of the lens holder 16 is connected to the objective lens holding portion 16a and is formed in a rectangular frame shape on the right side (the other end side) in the X-axis direction. The frame-shaped portion 16b A square hole 16b1 is drilled through.

  In addition, a focus coil 18 is wound and fixed in a square shape in a square hole 16b1 formed in the frame-shaped portion 16b of the lens holder 16, and the focus coil 18 has an objective lens holding portion 16a side. A pair of tracking coils 19 are fixed to the outer peripheral surface facing.

  In addition, a pair of coil wiring boards 20 are fixed to the left and right side surfaces of the frame-like portion 16b of the lens holder 16, and a total of four conductive suspension wires 21 are provided on the left and right pair of coil wiring boards 20 on the left, right, and upper sides. One end of each of the four suspension wires 21 is soldered so as to be electrically connected to the focus coil 18 and the pair of tracking coils 19, and the other end of the total of four suspension wires 21 is a wire support block on the fixed portion side. 14 is soldered to the wiring substrate 15 fixed to the back surface of the wire support block 14 while being supported on both the left and right sides of the wire 14 in a swingable manner.

  From the above, the movable part holds the objective lens 17 in the objective lens holding part 16a, and the lens holder 16 in which the focus coil 18 and the pair of tracking coils 19 are fixed in the square holes 16b1 of the frame-like part 16b. A total of four suspension wires 21 suspended between the lens holder 16 and the wire support block 14 in order to support the lens holder 16 in a swingable manner.

  Further, a rising mirror M inclined by 45 ° is disposed below the objective lens holding portion 16a of the lens holder 16, and the optical disk D is located above the objective lens 17 held in the objective lens holding portion 16a of the lens holder 16. A laser beam emitted from a semiconductor laser (not shown) is guided to an upper objective lens 17 by a rising mirror M, and the laser beam narrowed down by the objective lens 17 is a signal of the optical disc D. The return light irradiated on the surface in a spot shape and reflected by the optical disk D is detected by a photodetector (not shown) via the objective lens 17 and the rising mirror M.

  When the movable part is swingably supported with respect to the fixed part, the pair of magnets 12 and 13 fixed to the pair of upright pieces 11b and 11c of the base 11 are square holes of the frame-like part 16b of the lens holder 16. In this case, the magnet 12 fixed to one upright piece 11b is opposed to the pair of tracking coils 19 fixed in the square holes 16b1 of the frame-like portion 16b of the lens holder 16, and the base 11, the magnet 13 fixed to the other upright piece 11c is made to enter the focus coil 18 fixed in the square hole 16b1 of the frame-like portion 16b of the lens holder 16.

  At this time, the position of the center of gravity of the movable portion which is substantially parallel to the suspension direction of the total four suspension wires 21 and on the center line in the width direction of the lens holder 16 is the same as the focus coil 18 within the frame-like portion 16b of the lens holder 16. This is the vicinity of the portion where the pair of tracking coils 19 are joined.

  As a result, the operation of the objective lens driving device 10A according to the first embodiment having the above-described configuration applies a driving current to each of the focus coil 18 and the pair of tracking coils 19 fixed to the lens holder 16 on the movable part side, thereby fixing the fixed side. A total of four suspension wires 21 hold the objective lens 17 held in the lens holder 16 by the magnetic force in the focus direction and the magnetic force in the tracking direction generated between the pair of magnets 12 and 13 fixed to the base 11. The optical disc D is swung in the focus direction (Z-axis direction) and the tracking direction (Y-axis direction) through the optical disc D, and the return light from the optical disc D is detected while being detected by a photodetector (not shown). Feedback is applied to the coil 18 and the pair of tracking coils 19.

  Here, in the first embodiment, in order to maintain the focus servo characteristic for the objective lens 17 held in the lens holder 16 favorably, vibration having a frequency substantially the same as the high-order resonance frequency generated in the movable portion during the focus servo is absorbed. For example, a rubber adhesive 22 having such a characteristic is applied to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16 and then cured and fixed.

  At this time, the weight of the movable portion is about 240 mg, for example, and the total weight of the adhesive 22 applied to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16 is, for example, in the range of 0.6 mg to 4.2 mg. Therefore, it is most preferable that the application amount of the adhesive 22 is set within a range of 0.25% to 1.75% by weight with respect to the weight of the movable part. It is possible to satisfactorily dampen vibrations near the higher order resonance frequency.

  In addition, since the high-order resonance frequency is generated near 20 kHz, for example, at the time of focus servo, the movable part uses, for example, a one-part silicone RTV rubber KE3494 manufactured by Shin-Etsu Chemical Co., Ltd. as the adhesive 22. As shown in FIG. 2, the adhesive 22 has a characteristic of absorbing vibration in the vicinity of 20 kHz, for example, from the frequency characteristics with respect to GAIN and Phase. This has the effect of suppressing the Q value from decreasing with respect to the higher-order resonance frequency.

  Concretely, the comparative example with respect to Example 1 and Example 1 are demonstrated using FIG. 3 (a), (b).

  Here, in the comparative example shown in FIG. 3A, since the rubber adhesive 22 is not applied to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16, as shown in FIG. Frequency characteristics for GAIN and Phase can be obtained.

  On the other hand, in the first embodiment shown in FIG. 3B, since the rubber adhesive 22 is applied to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16, as shown in FIG. Frequency characteristics for GAIN and Phase can be obtained.

  From the above, comparing the comparative example shown in FIG. 3 (a) with the first embodiment shown in FIG. 3 (b), the GAIN having a high-order resonance frequency around 20 kHz, for example, generated during focus servo is performed more than the comparative example. It is clear that Example 1 is attenuated, and it can be seen that, for example, the Q value of the higher order resonance frequency near 20 kHz is improved.

  Furthermore, as shown in FIG. 4, when comparing the GAIN margin for higher-order resonance due to temperature, when the rubber adhesive 22 is not applied to the front left and right side surfaces of the objective lens holding portion 16 a of the lens holder 16. Changes drastically at a low temperature of 0 ° C. or less, and a GAIN margin cannot be obtained. On the other hand, when the rubber adhesive 22 is applied to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16, there is no significant change even in the range of -20 ° C to 40 ° C. GAIN margin enough to withstand use is obtained.

  Further, as shown in FIG. 4, when comparing frequency changes due to temperature, the case where the rubber adhesive 22 is not applied to the front left and right side surfaces of the objective lens holding portion 16 a of the lens holder 16 and the case of the rubber type Although it has the same inclination tendency as when the adhesive 22 is applied, the higher-order resonance frequency tends to be slightly higher when the rubber adhesive 22 is not applied.

  From the above, in the first embodiment, by applying and fixing the adhesive 22 to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16, high-order resonance around 20 kHz, for example, generated during focus servo is attenuated. Since the Q value can be lowered and the temperature characteristics with respect to the GAIN margin of higher order resonance can be maintained well, the objective lens driving device has a simple resonance countermeasure structure at the time of focus servo and good quality and reliability. 10A can be provided.

  Next, Modification 1 and Modification 2 in which the objective lens driving device 10A of Embodiment 1 is partially deformed will be described with reference to FIGS.

FIG. 5 shows the vibration of the movable portion in the focus direction at three measurement points Pa, Pb, and Pc when the movable portion is swung in the focus direction without applying an adhesive to the objective lens holding portion of the lens holder. A diagram schematically showing the state to be measured,
6A and 6B are diagrams schematically showing vibrations in the focus direction of the movable part measured at the three measurement points Pa, Pb, and Pc shown in FIG.
FIG. 7 is a perspective view showing an objective lens driving device of Modification 1 in which the objective lens driving device of Embodiment 1 is partially deformed;
FIG. 8 is a perspective view illustrating an objective lens driving device according to a second modification in which the objective lens driving device according to the first embodiment is partially deformed.

  As shown in FIG. 5, the lens holder 16 on the movable part side is attached to the movable part side via a plurality of suspension wires 21 on the base 11 on the fixed part side without applying the adhesive 22 to the objective lens holding part 16 a of the lens holder 16. When the lens holder 16 is swung in the focus direction, vibration detection sensors (not shown) are installed at positions of the three measurement points Pa, Pb, and Pc above the lens holder 16, and the lens The vibration in the focus direction of the holder 16 is detected.

  At this time, among the three measurement points Pa, Pb, and Pc, the measurement point Pa is a position on the front end side of the objective lens holding portion 16a of the lens holder 16, and the measurement point Pb is the position of the plurality of suspension wires 21. Near the center of gravity of the movable part that is substantially parallel to the suspension direction and on the center line in the width direction of the lens holder 16, the measurement point Pc is the position on the rear end side of the frame-like part 16b of the lens holder 16, in other words. The one end side of the lens holder 16 is the Pa position and the other end side is the Pc position with the measurement point Pb serving as the gravity center position of the movable portion interposed therebetween.

  When vibration in the focus direction of the lens holder 16 is detected at each of the three measurement points Pa, Pb, and Pc, as shown in FIGS. 6A and 6B, the movable portion (lens holder) ) On the front end side (measurement point Pa) of the objective lens holding portion 16a of the lens holder 16 and the position on the rear end side (measurement point Pc) of the frame-like portion 56b. For example, the phase of the higher-order resonance near 20 kHz is in phase, while the measurement point Pb is in reverse phase with respect to the measurement points Pa and Pc. At this time, the vibration in the focus direction of the movable part (lens holder) has a convex characteristic as shown in FIG. 6A or a concave characteristic as shown in FIG. 6B. Is.

  Therefore, since the measurement point Pa and the measurement point Pc are in phase as shown in FIGS. 6A and 6B, a modification in which the first embodiment is partially modified as shown in FIG. In the first objective lens driving device 10B, an adhesive 22 having a characteristic of absorbing vibration having substantially the same frequency as the high-order resonance frequency generated in the movable portion during focus servo is applied to the rear end portion of the frame-like portion 16b of the lens holder 16. It is clear that the same effect as in Example 1 can be obtained by applying and applying substantially the same amount as in Example 1 and then curing and fixing.

  Further, as shown in FIG. 8, in the objective lens driving device 10C according to the second modification obtained by partially deforming the first embodiment, the vibration having substantially the same frequency as the high-order resonance frequency generated in the movable portion during the focus servo is absorbed. By applying the adhesive 22 having characteristics to the front left and right side surfaces of the objective lens holding portion 16a of the lens holder 16 and the rear end portion of the frame-like portion 16b of the lens holder 16 and then curing and fixing them, The focus servo characteristics can be further improved as compared with the first embodiment and the first modification of the first embodiment.

FIG. 9 is a perspective view showing an objective lens driving device according to Example 2 of the present invention;
FIG. 10 is a perspective view showing an objective lens driving device of Modification 1 in which the objective lens driving device of Embodiment 2 is partially deformed;
FIG. 11 is a perspective view illustrating an objective lens driving device according to a second modification in which the objective lens driving device according to the second embodiment is partially deformed.

  As shown in FIG. 9, the objective lens driving device 30 </ b> A according to the second embodiment of the present invention is also applied with the moving circuit method (MC method) magnetic circuit means as in the first embodiment, and the fixed portion and the fixed portion are fixed. Although it is composed of a movable part that swings above the part, the shape of the lens holder 36 on the movable part side is different from that of Example 1 as described later.

  In the objective lens driving device 30A according to the second embodiment of the present invention described above, first, the fixed portion side will be described. A base 31 serving as a base of the device 30A is formed by bending using an iron material or a soft magnetic material. Yes.

  A laser beam passage hole 31a1 is formed through the front side on the upper surface 31a of the base 31, and a pair of upright pieces 31b and 31c are arranged on the X axis before and after the laser beam passage hole 31a1 is interposed therebetween. It is formed by cutting and raising upward and facing each other at a distance substantially parallel to the orthogonal Y axis, and a pair of magnets 32 and 33 face each other on the pair of standing pieces 31b and 31c. The lens holder 36, which will be described later, can enter between the pair of magnets 32, 33.

  Further, a wire support block 34 formed using a resin material is fixed on the upper surface 31a of the base 31 behind a lens holder 36 to be described later by using an adhesive (not shown), and this wire support block. A wiring board 35 is fixed to the back surface of 34.

  From the above, the fixed portion is composed of the base 31, the pair of magnets 32 and 33 fixed to the pair of standing pieces 31 b and 31 c, the wire support block 34, and the wiring board 35.

  Next, the movable part side will be described. Unlike the first embodiment, the lens holder 36 is formed in a rectangular shape using a resin material so that the front and rear dimensions and the left and right dimensions are substantially symmetrical.

  The lens holder 36 has a stepped round hole 36a penetrating through a central portion thereof, and an objective lens 37 is fixedly held in the stepped round hole 36a using an adhesive (not shown). Yes.

  In addition, a pair of coil wiring boards 38 and 39 are fixed to the front and rear surfaces of the lens holder 36. The pair of coil wiring boards 38 and 39 includes a focus coil 38a (39a, not shown) and tracking. Coils 38b (39b... Not shown) are wound and wired.

  In addition, a total of four wire support portions 36b are formed on the upper and lower sides of the left and right side surfaces of the lens holder 36 so as to protrude outwardly, and a total of four wire support portions 36b are provided in the left, right, upper and lower sides. Each end of the suspension wire 40 having the above conductivity is soldered so as to be electrically connected to the focus coils 38a, 39a and the tracking coils 38b, 39b, and then fixed with an adhesive. In addition, the other ends of the total of four suspension wires 40 are soldered to the wiring board 35 fixed to the back surface of the wire support block 34 while being supported swingably on both the left and right sides of the wire support block 34 on the fixed portion side. It is attached.

  From the above, the movable part holds the objective lens 37, and the lens holder 36 to which the pair of coil wiring boards 38 and 39 having the focus coils 38a and (39a) and the tracking coils 38b and (39b) are fixed, and the lens. A total of four suspension wires 40 suspended between the lens holder 36 and the wire support block 34 are provided to support the holder 36 in a swingable manner.

  Further, a rising mirror M inclined by 45 ° is disposed below the laser beam passage hole 31 a 1 of the base 31 facing the lens holder 36, and the optical disk D rotates above the objective lens 37 held in the lens holder 36. The laser beam emitted from a semiconductor laser (not shown) is guided to the upper objective lens 37 by the rising mirror M, and the laser beam narrowed down by the objective lens 37 is the signal surface of the optical disc D. Return light that is irradiated in a spot shape and reflected by the optical disk D is detected by a photodetector (not shown) via the objective lens 37 and the rising mirror M.

  When the movable part is swingably supported with respect to the fixed part, the lens holder 36 is inserted between the pair of magnets 32 and 33 fixed to the pair of upright pieces 31b and 31c of the base 31. At this time, the focus coils 38a, 39a and the tracking coils 38b, 39b wound around the pair of coil wiring boards 38, 39 fixed to the front and rear surfaces of the lens holder 36 are opposed to each other between the pair of magnets 32, 33. I am letting.

  At this time, the position of the center of gravity of the movable portion that is substantially parallel to the suspension direction of the total four suspension wires 40 and on the center line in the width direction of the lens holder 36 is determined by the front-rear dimension and the left-right dimension of the lens holder 36 as described above. Since it is substantially symmetric, it is substantially coincident with the optical axis of the objective lens 17.

  Thereby, the operation of the objective lens driving device 30A of Example 2 having the above-described configuration is performed by focusing the focus coils 38a, (39a) wound around the pair of coil wiring boards 38, 39 fixed to the lens holder 36 on the movable part side, and By applying a drive current to each of the tracking coils 38b and (39b), a magnetic force in the focus direction and a magnetic force in the tracking direction generated between the pair of magnets 32 and 33 fixed to the base 31 on the fixed side, The objective lens 37 held in the lens holder 36 is swung in the focus direction (Z-axis direction) and the tracking direction (Y-axis direction) with respect to the optical disk D via a total of four suspension wires 40, and the optical disk D Wound around a pair of coil wiring boards 38, 39 while detecting the return light from the light detector (not shown) Focusing coils 38a, (39a) and the tracking coils 38b, are fed back, respectively (39 b).

  Here, in Example 2, in order to maintain the focus servo characteristic for the objective lens 37 held in the lens holder 36 satisfactorily, vibrations having substantially the same frequency as the high-order resonance frequency generated in the movable part during focus servo are absorbed. For example, a rubber adhesive 41 having such characteristics is applied to the left and right front corners of the lens holder 36 and then cured and fixed.

  At this time, substantially the same as in Example 1, for example, one-part silicone RTV rubber KE3494 manufactured by Shin-Etsu Chemical Co., Ltd. can be used as the adhesive 41. The weight ratio is most preferably set in the range of 0.25% to 1.75%, and this can satisfactorily attenuate vibrations in the vicinity of the higher-order resonance frequency generated in the movable part during focus servo.

  From the above, in the second embodiment, by applying and fixing the adhesive 41 to the front left and right corner portions of the lens holder 36, a high-order resonance around 20 kHz, for example, generated during focus servo, as in the first embodiment. Since the Q value can be lowered by attenuating and the temperature characteristic with respect to the GAIN margin of higher order resonance can be maintained well as in the first embodiment, the resonance countermeasure structure at the time of focus servo is simple. The objective lens driving device 30A with good quality and reliability can be provided.

  Also in the second embodiment, as described above with reference to FIGS. 6A and 6B, the front side of the lens holder 36 with the optical axis of the objective lens 37 serving as the center of gravity of the movable portion interposed therebetween ( Since the phase of the higher-order resonance near 20 kHz, for example, at the position on the one end side) and the rear side (the other end side) is in phase, for example, as shown in FIG. In the objective lens driving device 30B of the first modified example, the adhesive 41 having the characteristic of absorbing vibrations having substantially the same frequency as the high-order resonance frequency generated in the movable part during focus servo is applied to the left and right corner portions of the lens holder 36. It is clear that the same effect as in Example 2 can be obtained by applying and applying substantially the same amount as in Example 2 and then curing and fixing.

  Furthermore, as shown in FIG. 11, in the objective lens driving device 30C according to the second modification obtained by partially deforming the second embodiment, the vibration having substantially the same frequency as the high-order resonance frequency generated in the movable portion during the focus servo is absorbed. The adhesive 41 having the characteristics is applied to the front left and right corner portions of the lens holder 36 and the rear left and right corner portions of the lens holder 36, and then cured and fixed. The focus servo characteristic can be further improved as compared with the first modification.

FIG. 12 is a perspective view showing an objective lens driving device according to Example 3 of the present invention;
FIG. 13 is a perspective view showing an objective lens driving device of Modification 1 in which the objective lens driving device of Embodiment 3 is partially deformed;
FIG. 14 is a perspective view showing an objective lens driving device of Modification 2 in which the objective lens driving device of Embodiment 3 is partially deformed.

  As shown in FIG. 12, the objective lens driving device 50A according to the third embodiment of the present invention applies a magnetic circuit means using a moving magnet method (MM method), and swings above the fixed portion. And a movable part.

  In the objective lens driving device 50A according to the third embodiment of the present invention described above, first, the fixed portion side will be described. A base 51 serving as a base of the device 50A is bent using an iron material or a soft magnetic material. Yes.

  On the upper surface 51a of the base 51, an upright piece 51b is raised upward substantially parallel to the Y axis perpendicular to the X axis, and is wound around the upright piece 51b in a square shape. The focus coil 52 is fixed, and a plurality of tracking coils 53 are fixed before and after the outer peripheral surface of the focus coil 52. The focus coil 52 and the plurality of tracking coils 53 are frame-shaped portions of a lens holder 56 described later. It faces the square hole 56b1 formed in 56b.

  In addition, a wire support block 54 formed using a resin material is fixed on the upper surface 51a of the base 51 behind a frame-like portion 56b of a lens holder 56 described later using an adhesive (not shown). The wiring board 55 is fixed to the back surface of the wire support block 54, and the lead wires of the focus coil 52 and the plurality of tracking coils 53 pass through the notch holes 54 a formed in the wire support block 54. Soldered.

  From the above, the fixed portion is composed of the base 51, the focus coil 52 and the plurality of tracking coils 53 fixed to the standing piece 51 b of the base 51, the wire support block 54, and the wiring board 55.

  Next, the movable part side will be described. In the lens holder 56, the objective lens holding part 56a and the frame-like part 56b are integrally formed using a resin material.

  At this time, the objective lens holding portion 56a of the lens holder 56 is formed on the left side (one end side) in the X-axis direction with a reduced thickness in the height direction. A stepped round hole 56a1 is formed through the inside, and the objective lens 57 is fixedly held in the stepped round hole 56a1 using an adhesive (not shown).

  Further, the frame-shaped portion 56b of the lens holder 56 is connected to the objective lens holding portion 56a and is formed in a rectangular frame shape on the right side (the other end side) in the X-axis direction, and this frame-shaped portion 56b. A square hole 56b1 is drilled through the inside of the inside.

  In addition, a pair of magnets 58 and 59 are spaced apart from each other in the square hole 56b1 formed in the frame-like portion 56b of the lens holder 56 and face each other so as to be substantially parallel to the Y axis perpendicular to the X axis. (Not shown).

  In addition, a total of four wire support portions 56b2 are formed to protrude outward on the left and right side surfaces of the frame-shaped portion 56b of the lens holder 56, respectively. One end of each of the four suspension wires 60 is fixed using an adhesive in the vertical direction, and the other end of each of the four suspension wires 40 swings to the left and right sides of the wire support block 54 on the fixed portion side. While being supported freely, it is soldered to the wiring board 55 fixed to the back surface of the wire support block 54.

  From the above, the movable part holds the objective lens 57 in the objective lens holding part 56a and fixes the pair of magnets 58 and 59 in the square hole 56b1 of the frame-like part 56b, and the lens holder 56. Is composed of four suspension wires 60 suspended between the lens holder 56 and the wire support block 54.

  Further, a rising mirror M inclined by 45 ° is disposed below the objective lens holding part 56a of the lens holder 56, and the optical disk D is located above the objective lens 57 held in the objective lens holding part 56a of the lens holder 56. A laser beam emitted from a semiconductor laser (not shown) is guided to an upper objective lens 57 by a rising mirror M, and the laser beam narrowed down by the objective lens 57 is a signal of the optical disc D. The return light irradiated on the surface in a spot shape and reflected by the optical disk D is detected by a photodetector (not shown) via the objective lens 57 and the rising mirror M.

  When the movable part is swingably supported with respect to the fixed part, the focus coil 52 and the plurality of tracking coils 53 fixed to the standing piece 51b of the base 51 are connected to the square hole 56b1 of the frame-like part 56b of the lens holder 56. At this time, the focus coil 52 and the plurality of tracking coils 53 are opposed to a pair of magnets 58 and 59 fixed in the square hole 56b1 of the frame-like portion 56b of the lens holder 56.

  At this time, the position of the center of gravity of the movable portion that is substantially parallel to the suspension direction of the total four suspension wires 60 and on the center line in the width direction of the lens holder 56 is fixed to the fixed portion side in the frame-like portion 56 b of the lens holder 56. The intermediate portion is substantially corresponding to the upright piece 51b of the base 51.

  Thereby, the operation of the objective lens driving device 50A according to the third embodiment having the above-described configuration applies a driving current to each of the focus coil 52 and the plurality of tracking coils 53 fixed to the standing piece 51b of the base 51 on the fixed portion side. In the lens holder 56, the magnetic force in the focusing direction and the magnetic force in the tracking direction generated between the pair of magnets 58 and 59 fixed in the square hole 56b1 of the frame-like portion 56b of the lens holder 56 on the movable portion side. The objective lens 57 held on the optical disk D is swung in the focus direction (Z-axis direction) and the tracking direction (Y-axis direction) with respect to the optical disk D via a total of four suspension wires 60 to return light from the optical disk D. The focus coil 52 and the plurality of tracking coils 53 are detected while the light is detected by a photodetector (not shown). Each is multiplied by the feedback.

  Here, in the third embodiment, in order to maintain the focus servo characteristic for the objective lens 57 held in the lens holder 56 satisfactorily, vibrations having substantially the same frequency as the higher-order resonance frequency generated in the movable part during focus servo are absorbed. For example, a rubber-based adhesive 61 having such characteristics is applied to the front left and right side surfaces of the objective lens holding portion 56a of the lens holder 56, and then cured and fixed.

  At this time, since the pair of magnets 58 and 59 are fixed to the front and rear in the square hole 56b1 of the frame-like portion 56b of the lens holder 56, the weight of the movable portion becomes heavier than those of the first and second embodiments. Since the rigidity of the lens holder 56 is increased, the higher-order resonance frequency generated in the movable part during focus servo is higher than that in the first and second embodiments, for example, around 25 kHz. Therefore, the material of the adhesive 61 is selected according to this. It ’s good.

  From the above, in the third embodiment, by applying and fixing the adhesive 61 to the front left and right side surfaces of the objective lens holding portion 56a of the lens holder 56, high-order resonance around 25 kHz, for example, generated during focus servo is attenuated. Since the Q value can be lowered and the temperature characteristics with respect to the GAIN margin of higher order resonance can be maintained well as in the first embodiment, the resonance countermeasure structure at the time of focus servo is simple, and the quality and reliability. Can provide the objective lens driving device 50A.

  In the third embodiment as well, as described above with reference to FIGS. 6A and 6B, the intermediate portion position in the frame-like portion 56b of the lens holder 56 serving as the center of gravity of the movable portion is sandwiched. The phase of the higher-order resonance, for example, around 25 kHz is in phase at the position of the front end side (one end side) of the objective lens holding portion 56a of the lens holder 56 and the position of the rear end side (the other end side) of the frame-like portion 56b. Therefore, as shown in FIG. 13, in the objective lens driving device 50B of the first modification obtained by partially deforming the third embodiment, the vibration having substantially the same frequency as the high-order resonance frequency generated in the movable portion during the focus servo. It is clear that the same effect as that of the third embodiment can be obtained by applying the adhesive 61 having the property of absorbing water to the rear end portion of the frame-like portion 56b of the lens holder 56 and then curing and fixing the adhesive. .

  Further, as shown in FIG. 14, in the objective lens driving device 50C according to the second modification obtained by partially deforming the third embodiment, the vibration having the substantially same frequency as the high-order resonance frequency generated in the movable portion during the focus servo is absorbed. By applying the adhesive 61 having characteristics to the front left and right side surfaces of the objective lens holding portion 56a of the lens holder 56 and the rear end portion of the frame-like portion 56b of the lens holder 56, and then curing and fixing them, The focus servo characteristics can be further improved as compared with the third embodiment and the first modification of the third embodiment.

  In the objective lens driving device according to the first to third embodiments described in detail above, the lens is sandwiched between the gravity center positions of the movable portions that are substantially parallel to the suspension direction of the plurality of suspension wires and are on the center line in the width direction of the lens holder. A common technical idea is that at least one of the one end side and the other end side of the holder is fixed with an adhesive having a characteristic of absorbing vibrations in the vicinity of a higher-order resonance frequency generated in the movable part during focus servo. Is.

  At this time, the adhesives 22, 41 and 61 used in Examples 1 to 3 are not limited to the rubber system such as the above-described silicon RTV rubber. The composition system is not limited as long as the adhesive has a characteristic of satisfactorily attenuating the vibration of the higher-order resonance frequency of the movable part. Further, the adhesive most preferably has a damping peak with respect to a frequency substantially equal to the higher-order resonance frequency of the movable part as a damping characteristic.

  Further, the curing system for the adhesives 22, 41, 61 is not limited. It is not limited to the room temperature curable type of the embodiment, and may be, for example, a photo curable type or a heat curable type.

It is the perspective view which showed the objective lens drive device of Example 1 which concerns on this invention. It is the figure which showed the frequency characteristic of the rubber-type adhesive agent used for the objective-lens drive device of Example 1 which concerns on this invention. In the objective lens drive device of Example 1 which concerns on this invention, it is a frequency characteristic figure for demonstrating a focus servo characteristic, (a) is apply | coating a rubber-type adhesive agent to the objective lens holding part of a lens holder as a comparative example (B) is a diagram showing a case where a rubber adhesive is applied to the objective lens holding portion of the lens holder as Example 1. FIG. In the objective lens driving device of Example 1 according to the present invention, it is a characteristic diagram for explaining the GAIN margin of higher-order resonance and the frequency change due to temperature. As a comparative example, the objective lens holding portion of the lens holder is made of a rubber system. FIG. 2 is a diagram showing a case where an adhesive is not applied, as a solid line, and a case where a rubber adhesive is applied to an objective lens holding portion of a lens holder as Example 1 as a dotted line. A state in which the vibration in the focus direction of the movable part is measured at three measurement points Pa, Pb, and Pc when the movable part is swung in the focus direction without applying an adhesive to the objective lens holding part of the lens holder. FIG. (A), (b) is the figure which showed typically the vibration of the focus direction of the movable part measured at three measurement points Pa, Pb, Pc shown in FIG. It is the perspective view which showed the objective-lens drive device of the modification 1 which deform | transformed the objective-lens drive device of Example 1 partially. It is the perspective view which showed the objective-lens drive device of the modification 2 which partially deformed the objective-lens drive device of Example 1. FIG. It is the perspective view which showed the objective lens drive device of Example 2 which concerns on this invention. FIG. 10 is a perspective view showing an objective lens driving device of Modification 1 in which the objective lens driving device of Example 2 is partially deformed. It is the perspective view which showed the objective-lens drive device of the modification 2 which partially deformed the objective-lens drive device of Example 2. FIG. The perspective view which showed the objective-lens drive device of Example 3 which concerns on this invention, It is the perspective view which showed the objective-lens drive device of the modification 1 which deform | transformed the objective-lens drive device of Example 3 partially. It is the perspective view which showed the objective-lens drive device of the modification 2 which deform | transformed the objective-lens drive device of Example 3 partially.

Explanation of symbols

10A: objective lens driving device of Example 1,
10B: Objective lens driving device of Modification 1 obtained by partially deforming Embodiment 1;
10C: Objective lens driving device of Modification 2 in which Example 1 is partially deformed,
11 ... Base, 11a ... Upper surface, 11b, 11c ... A pair of upright pieces,
12, 13 ... a pair of magnets, 14 ... a wire support block, 15 ... a wiring board,
16 ... lens holder,
16a ... Objective lens holding part, 16a1 ... Round hole with step, 16b ... Frame-like part, 16b1 ... Square hole,
17 ... Objective lens, 18 ... Focus coil, 19 ... Tracking coil,
20 ... Coil wiring board, 21 ... Suspension wire, 22 ... Adhesive,
30A: Objective lens driving device of Example 2,
30B ... Objective lens driving device of Modification 1 in which Embodiment 2 is partially deformed,
30C: Objective lens driving device of Modification 2 obtained by partially deforming Embodiment 2;
31 ... Base, 31a ... Upper surface, 31a1 ... Laser beam passage hole,
31b, 31c ... standing piece, 32, 33 ... a pair of magnets,
34 ... wire support block, 35 ... wiring board,
36 ... Lens holder, 36a ... Round hole with step, 36b ... Wire support part,
37 ... objective lens, 38, 39 ... a pair of coil wiring boards,
38a, (39a) ... focus coil, 38b, (39b) ... tracking coil,
40 ... suspension wire, 41 ... adhesive,
50A: Objective lens driving device of Example 3,
50B: Objective lens driving device of Modification 1 in which Example 3 is partially deformed,
50C: Objective lens driving device of Modification 2 in which Example 3 is partially deformed,
51 ... Base, 51a ... Upper surface, 51b ... Standing piece,
52 ... Focus coil, 53 ... Tracking coil,
54 ... Wire support block, 55 ... Wiring board,
56 ... Lens holder,
56a ... objective lens holding portion, 56a1 ... stepped round hole, 56b ... frame-like portion, 56b1 ... square hole,
57 ... objective lens, 58, 59 ... a pair of magnets,
60 ... Suspension wire, 61 ... Adhesive,
D: Optical disk, M: Launch mirror.

Claims (5)

A fixed portion having a wire support block;
Comprising a lens holder having an objective lens holder on which an objective lens is held the objective lens holding portion is a frame-shaped portion connected to one end of the plurality of suspension wires to the frame-like portion is fixed respectively, said plurality a movable part which is swingable with respect to the fixed part the other end of the suspension wires is respectively supported on the wire support block,
Magnetic drive means for swinging the movable part in a focus direction and a tracking direction with respect to the signal surface of the optical recording medium via the plurality of suspension wires;
Equipped with a,
An adhesive having a characteristic of absorbing vibrations in the vicinity of the high-order resonance frequency generated in the movable part during focus servo is fixed to a position in the vicinity of the objective lens in the objective lens holding part. Objective lens drive. 2. The objective lens driving device according to claim 1, wherein the adhesive is also fixed to a position on the opposite side of the frame-shaped portion across the center of gravity of the movable portion. It said magnetic drive means, the magnet is fixed to the fixing portion, and, according to claim 1 or claim 2 focusing and tracking coils to the frame-like portion of the lens holder is characterized in that it is fixed Objective lens drive device. Said magnetic drive means, said focusing coil and tracking coils are fixed to the fixing portion, and, according to claim 1 or claim 2 magnet on the frame-like portion of the lens holder is characterized in that it is fixed Objective lens drive device. The coating amount of the adhesive, any of claim 1 to claim 4, characterized in that the weight ratio relative to the weight of the movable portion is in the range of 0.25% to 1.75% The objective lens driving device according to claim 1.

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