JP2006244629A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a coil wire is wound in a groove portion of a lens holder, the coil wire is hooked on an edge portion of the groove portion, so that the coil wire is cut. <P>SOLUTION: The groove portion is composed of a pair of bottom portion side walls 2f and 2g perpendicular to a bottom portion 2e of the groove portion formed in the lens holder 2, a pair of opening portion side walls 2c and 2d forming an opening portion facing the bottom portion 2e, and a pair of inclined side walls 2h and 2i connecting the opening portion side walls 2c and 2d and the bottom portion side walls 2f and 2g, respectively. Thereby, it is possible to solve the problem that, when the wire 18 is wound in the groove portion, the wire 18 abuts on the edge portion 2a or 2b and is easily cut. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup for recording and reproducing by projecting a light spot on a disk.

  An information medium that can be optically recorded and / or reproduced is recorded and reproduced in a non-contact manner by an optical pickup that includes a light source and an objective lens that focuses light emitted from the light source on a concession layer of the information medium. In short, FIG. 2 shows a general configuration of an optical pickup. In the figure, reference numeral 1 denotes an objective lens, 2 a lens holder for holding the objective lens 1, and the lens holder 2 has a focus coil 3 and a radial direction 17 with respect to the disc in a direction perpendicular to the disc (not shown). Two tracking coils 4a and 4b are fixed in the same direction with respect to the shaft. Spring substrates 6a to 6d (6d is hidden by the lens holder 2) are fixed to the lens holder 2, and four suspensions for holding the lens holder 2 in a cantilever manner are attached to the spring substrates 6a to 6d. Wires (metal wire springs) 7a to 7d are fixed by solder. An actuator substrate (hereinafter referred to as an ACT substrate) 8 is fixed to the bent portion 12 a of the actuator base 12 together with the suspension holder 9 by screws 36.

  The other ends of the four suspension wires 7a to 7d are fixed to the ACT substrate 8 integrally fixed to the suspension holder 9 by passing through the suspension holder 9 and soldered to the lens holder 2. Is movable in two axial directions, a vertical direction 16 and a radial direction 17 with respect to the disk.

  A pair of magnets 11 a and 11 b magnetized in the same direction as the disk tangential direction 15 are attached to the actuator base 12 in close proximity to the coils 4 a and 4 b wound around the lens holder 2. When a current flows through the focus coil 3 and / or the tracking coils 4a and 4b (hereinafter collectively referred to as coils), the lens holder 2 moves in the vertical direction 16 and the radial direction 17 with respect to the disk. Further, the start and end of the focus coil 3 and the tracking coil 4 are soldered to the spring substrates 6a to 6d, respectively, and soldered to the ACT substrate 8 via the suspension wires 7a to 7d. A terminal is electrically connected to the two types of coils 3, 4a, 4b. The suspension holder 9 is fixed to the actuator base 12, and the actuator base 12 is configured substantially parallel to the disk to form an objective lens driving device. This objective lens driving device is adjusted and fixed at the best position with respect to the optical bench 19. That is, the actuator base 12 is urged against the ACT spring 13 by screwing the screw 37 to the optical bench 19 and is adjusted and fixed by the tilt adjusting screws 38 and 39. A rising mirror 23 is attached to the optical bench 19.

  A semiconductor laser unit 25 is mounted on the flexible substrate unit 24 in the direction opposite to the laser emission direction. A heat radiating plate 27 is fixed to the back side of the semiconductor laser unit 25, and the heat generated by the semiconductor laser unit 25 is radiated by the heat radiating plate 27.

  The flexible substrate unit 24 is mounted in the optical bench 19 so as to be rotatable about the optical axis of the semiconductor laser unit 25 in a substantially tangential direction 15 of the disk in a plane substantially perpendicular to the disk. The light emitted from the semiconductor laser unit 25 is bent in the vertical direction 16 with respect to the disk by the rising mirror 23 and is incident on the objective lens 1. The semiconductor laser unit 25 and the heat radiating plate 27 are pressed and fixed to the optical bench 9 so as to be held between the unit pressing springs 14. An ACT cover 5 is fixed to the actuator base 12 so as to protect the lens holder 2.

  In the configuration of the optical pickup as described above, the focus coil 3 that adjusts the direction perpendicular to the disk (that is, the focus direction) by the spot where the light emitted from the semiconductor laser unit 25 is collected by the objective lens 1 and the disk The tracking coils 4a and 4b for adjusting the radial direction (ie, tracking direction) of the lens holder 2 need to be fixedly wound around the lens holder 2 in order to stabilize the focus characteristic and the tracking characteristic. As a technique for fixing and winding the coil around the lens holder 2, for example, Patent Document 1 discloses a technique in which the lens holder 2 includes a winding groove for the focus coil 3.

FIG. 3 is a cross-sectional configuration diagram illustrating the configuration of the focus coil winding groove disclosed in Patent Document 1 in accordance with the shape of FIG. In the drawing, 2 is a lens holder, 2a and 2b are edge portions of focus coil winding grooves provided in the lens holder 2, 2e is a bottom portion of the groove portion, 2j and 2k are bottom side walls, and 18 is a focus coil winding. In Patent Document 1, as shown in the same figure, the bottom surface 2e and the opening facing the bottom surface 2e have the same width (in other words, the distance between the pair of bottom side walls 2j and 2k is the distance between the openings). It is. After winding the windings 18 sequentially from the bottom 2e in the groove portion having such a configuration, the winding 18 is melted by a method such as energization heating to integrate the windings 18 together. The focus coil 3 is fixed to the lens holder 2. As shown in the figure, the fixed focus coil 3 has no space for the winding 18 to move in any direction of the bottom side walls 2j and 2k. The focus control characteristic is not changed by moving 3 in the groove.
JP-A-11-283261

  However, in the focus coil winding groove disclosed in Patent Document 1, in the process of winding the winding wire 18 in the groove portion, the winding wire 18 is inevitably caught on the edge portion 2a or 2b, and the winding wire 18 is frequently cut. In the edge portions 2a and 2b, a molding defect generally referred to as a burr is easily generated in the groove forming process, and this burr facilitates the catching of the winding 18 in the winding process and is more likely to be cut. If the winding 18 is cut in the winding process, the function as the focus coil 3 cannot be performed, so that the winding is re-started from the beginning, and the already wound winding 18 is wasted. There was a problem that took time.

  In order to solve the problem of Patent Document 1, the winding 18 is wound around the groove portion having the configuration shown in FIG. That is, the groove part of the figure has a configuration including a pair of bottom side walls 21 and 2m wider than the winding width of the focus coil 3 by S + T. With the configuration shown in the figure, it is possible to suppress the winding 18 from being caught by the edge portion 2a or 2b in the winding process of the winding 18, and the time required for the winding process can be shortened. Waste can be greatly reduced. When the width direction differences S and T are increased, winding becomes easier, but in order to maintain the strength of the lens holder 2, the optical axis direction of the objective lens 1 of the lens holder 2 (omitted in FIG. 4, see FIG. 2). Thus, the lens holder 2 is equivalently enlarged. Therefore, in order to meet the demand for downsizing of the optical pickup, it is necessary to make S and T as small as possible. From the viewpoint of easy winding and maintaining the strength of the lens holder 2, S + T is converted into the diameter of the winding 18. It was about two.

  With the configuration of the groove portion shown in the figure, as described above, the maintenance of the strength of the lens holder 2 and the ease of winding the winding 18 are compatible. However, when a focus drive current is passed through the focus coil 3, the focus coil 3 generates heat, and the adhesion between the interface between the focus coil 3 and the bottom 2e and / or the adhesion between the windings 18 is weakened. The fixing force between the windings 18 is melting of the same material and the windings 18 are closely packed, so the possibility that the fixing force is weakened is very low, but the interface between the focus coil 3 and the bottom 2e is made of different materials. As can be seen from the figure, the fixing at the contact point between the winding 18 and the bottom 2e (the winding 18 is cylindrical, but not linear but linear) is inherently weak, and in the groove The windings 18 of the focus coil 3 formed in this way generate heat evenly, but the winding closer to the bottom 2e is combined with the poorer heat radiation efficiency, and the fixing strength at the interface is relatively easily reduced. Other than that, since the material of the insulating layer of the winding 18 is different from the material used for the lens holder 2, the fixing strength is weakened due to the change with time.

  When a drive current is passed through the focus coil 3 in a state where the fixing strength at the interface between the bottom 2e and the focus coil 3 is weakened, the focus coil 3 exerts a force according to the magnetic field formed by the magnets 11a and 11b (see FIG. 2). In response, the responsiveness when operating the lens holder 2 according to the force is deteriorated. That is, when the bottom portion 2e and the focus coil 3 are not fixed, a driving force is applied to the lens holder 2 after the focus coil 3 is displaced by S or T along the bottom portion 2e. In other words, in terms of focus servo, it is mechanical. There is a problem that the offset is superimposed. Such a problem occurs not only at the focus coil 3 but also at each interface between the tracking coils 4 a and 4 b and the lens holder 2.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to improve the fixing force between the focus coil and tracking coil and the lens holder due to change with time and / or heat generation.

  An optical pickup according to the present invention includes an objective lens, a focus coil and a tracking coil wound to drive the objective lens in two directions of a perpendicular direction and a radial direction with respect to a disk, the objective lens, the focus coil, A lens holder that integrally holds the tracking coil, and one end that supports the lens holder are fixed to the lens holder so that the objective lens can be moved in two directions of a perpendicular direction and a radial direction with respect to the disk. Four suspension wires, an actuator substrate to which the other ends of the four suspension wires are fixed, a suspension holder made of a resin material for fixing the actuator substrate, and the lens holder in two axes facing the coil And a magnet for driving the magnet And an actuator base that fixes and holds the suspension holder and protects the lens holder and the suspension wire, a semiconductor laser unit, a flexible substrate on which the semiconductor laser unit can be mounted in the back direction from the light emitting side, and the semiconductor A laser unit is rotatably mounted with the optical axis as a central axis in the light emission side direction, and an optical bench that adjusts and holds the actuator base, and the light emitted from the semiconductor laser unit on the optical bench is the objective An optical system that is incident on the lens, and a groove portion around which the focus coil and / or the tracking coil is wound is formed with a predetermined groove depth from the surface of the lens holder, and the groove portion includes a bottom portion and the bottom portion. From a pair of opposite sides to the bottom A pair of bottom sidewalls formed directly and a pair of parallel sidewall openings forming an opening facing the bottom, and the distance between the pair of sidewalls is greater than the distance between the pair of bottom sidewalls. And a pair of inclined side walls connecting the pair of opening side walls and the pair of bottom side walls.

  Since the optical pickup according to the present invention includes a pair of opening side walls having a gap wider than the gap between the pair of bottom side walls, when the focus coil or the tracking coil is wound from the opening into the groove, the wire at the edge While suppressing the cutting, it is possible to suppress the shift or vibration of the focus coil or the tracking coil in the groove due to the change over time or heat generation, and there is an effect of exhibiting excellent characteristics in focus responsiveness and track responsiveness.

  The optical pickup according to the present invention has a winding by making the width of the pair of bottom side walls forming the bottom of the groove around which the focus coil or the tracking coil is wound smaller than the width of the pair of opening side walls forming the opening. Sometimes it can be wound so that the coil wire does not touch the edge, and if the focus coil or tracking coil is integrated by a method such as energizing and fixing after winding, it will be sandwiched between the pair of bottom side walls It can be held and does not vibrate in the groove. Further, since the continuous surface is formed by the inclined side wall, the inclined side wall can guide the winding to the winding position as a guide, and the winding of the focus coil or the tracking coil can be stabilized.

  Next, a preferred embodiment of the optical pickup of the present invention will be described in detail with reference to FIG. This figure is a partial cross-sectional view of a groove portion around which the focus coil 3 of the lens holder 2 is wound. 2e is a bottom portion, 2a and 2b are edge portions of an opening facing the bottom portion 2e, and 2c and 2d form an opening portion. A pair of parallel opening side walls 2f and 2g are a pair of bottom side walls formed perpendicular to the bottom 2e, and 2h and 2i are a pair of opening side walls 2c and 2d and a pair of bottom side walls 2f and 2g, respectively. It is an inclined side wall.

  In the step of forming the focus coil 3 by winding the winding 18 in the groove portion having such a configuration, the winding 18 can be wound without being caught on the edge portion 2a or 2b. After the winding of the windings 18 is finished, the windings 18 generate heat, for example, by passing an electric current, and the windings 18 and the bottom 2e and the windings 18 are melted (insulation coating portion of the windings 18 is melted). The focus coil 3 can be obtained.

  In the focus coil 3 of the present embodiment, the fixation at the interface between the bottom 2e and the focus coil 3 not only melts the insulation coating portion of the winding 18, but also defines the width direction of the focus coil 3 by a pair of bottom side walls. As described with reference to FIG. 4, even when the fixing strength is insufficient due to heat generation at the boundary between the bottom 2 e and the focus coil 3, since the regulating force in the width direction acts, the aforementioned focus offset occurs, Focus characteristics are not deteriorated.

  Since the groove part in this embodiment is provided with the opening part which has a width | variety wider than the width | variety of the bottom part 2e, thickness increase is assumed in order to maintain the mechanical strength of the lens holder 2 as demonstrated with reference to FIG. However, since the pair of inclined side walls 2h and 2i and the pair of bottom side walls 2f and 2g are provided, mechanical agreement can be suppressed. The difference (P + Q) between the width between the pair of bottom side walls 2 f and 2 g and the width between the pair of opening side walls 2 c and 2 d is preferably 3 to 5 times the diameter of the winding 18. Even if it is less than 3 times, the effect of reducing the catch in the winding process can be exhibited, but in order to make the reduction effect remarkable, at least 3 times or more is preferable. On the other hand, if it exceeds five times, the inclination angle of the pair of inclined side walls 2h and 2i with respect to the pair of bottom side walls 2f and 2g becomes large, and a tendency that the mechanical strength tends to decrease is observed. P and Q are generally set equal to each other. For example, a magnetic circuit generated by the magnetic field between the magnets 11a and 11b and the focus coil 3 is appropriately set depending on the installation position of the objective lens 1 in the optical axis center direction. Can be set.

The height R in the groove depth direction of the pair of bottom side walls 2f and 2g is (0.5 + 3 ^1/2 ) L or more (1 + 2 × 3 ^1/2 ), where L is the diameter of the winding 18 to be wound. ) L or less is preferable. Since the winding 18 of the focus coil 3 is generally wound in a close-packed manner, if R is less than (0.5 + 3 ^1/2 ) L, the winding 18 and R in FIG. As is clear from the relationship, there is a gap between the winding 18 at the right end of the drawing wound in the second row on the bottom 2e and the inclined side wall 2i, and the winding 18 and the bottom 2e in the first row If the fixing strength of is weakened, there is a risk that the focus coil 3 moves along the bottom portion 2e by the gap, and if R is set to exceed (1 + 2 × 3 ^1/2 ) L, the focus coil 3 is displaced. The suppression effect is the same as in the case of R = (1 + 2 × 3 ^1/2 ) L, and only the thickness of the lens holder 2 is increased. Therefore, the above range is preferable. However, although it is theoretically satisfactory as a function within the above-mentioned range, the range of 2L or more and 4L or less is desirable in view of the winding error of the winding device in actual production.

  In the above-described embodiment, the focus coil 3 has been described as an example. However, the tracking coils 4a and 4b are exactly the same, and of course, the same effect can be obtained.

  The optical pickup of the present invention can be widely applied to those having a configuration in which a movable part such as a lens is supported by four wires.

The principal part expanded sectional view in the optical pick-up of this invention Exploded perspective view showing configuration of optical pickup Main part enlarged sectional view explaining an example of a conventional optical pickup Main part expanded sectional view explaining other examples of the conventional optical pickup

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 2a, 2b Edge part 2c, 2d Opening side wall 2e Bottom part 2f, 2g Bottom side wall 2h, 2i Inclined side wall 3 Focus coil 4a, 4b Tracking coil 5 ACT cover 6a, 6b, 6c, 6d Spring board 7a , 7b, 7c, 7d Suspension wire 8 ACT board 9 Suspension holder 11a, 11b Magnet 12 Actuator base 13 ACT spring 14 Unit holding spring 19 Optical stand 23 Raising mirror 24 Flexible board unit 25 Semiconductor laser unit 27 Heat sink 38, 39 Air Adjustment screw

Claims (3)

An objective lens, a focus coil and a tracking coil wound to drive the objective lens in two directions of a perpendicular direction and a radial direction with respect to the disk, and the objective lens, the focus coil, and the tracking coil are integrated. A lens holder for holding, and four suspension wires fixed to the lens holder at one end for supporting the lens holder so that the objective lens can be moved in two directions of a perpendicular direction and a radial direction with respect to the disk; An actuator substrate to which the other ends of the four suspension wires are fixed; a suspension holder made of a resin material for fixing the actuator substrate; a magnet for driving the lens holder in two axes so as to face the coil; The magnet and the suspension holder An actuator base for fixing and holding the lens holder and the suspension wire, a semiconductor laser unit, a flexible substrate on which the semiconductor laser unit can be mounted on the light emitting side in the back direction, and the semiconductor laser unit An optical bench that is rotatably mounted with the optical axis as the central axis in the light emitting side direction, and that adjusts and holds the actuator base, and the light emitted from the semiconductor laser unit is incident on the objective lens on the optical bench An optical system
A groove portion for winding the focus coil and / or the tracking coil is formed at a predetermined groove depth from the surface of the lens holder,
The groove includes a bottom, a pair of bottom side walls formed perpendicular to the bottom from a pair of opposite sides of the bottom, and a pair of parallel opening side walls that form an opening facing the bottom. Including
An interval between the pair of opening side walls is wider than an interval between the pair of bottom side walls, and includes a pair of inclined side walls that connect the pair of opening side walls and the pair of bottom side walls. When the diameter of the focus coil or the tracking coil wound around the groove is L, the height of the pair of bottom side walls from the bottom to the opening is (0.5 + 3 ^1/2 ) L or more (1 + 2) 2. The optical pickup according to claim 1, wherein the optical pickup is equal to or less than × 3 ^1/2 ) L. The width of the width between the pair of inclined side walls with respect to the width between the bottom side walls is 3L or more and 5L or less, where L is the diameter of the focus coil or the tracking coil wound around the groove. The optical pickup according to any one of the above.

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