JP4398892B2 - Objective lens drive - Google Patents

Description

  The present invention relates to an objective lens driving device of an optical pickup that records and / or reproduces information with an objective lens held by a lens holder facing an optical disk such as a DVD, and in particular, the lens holder has a conductive wire. And an objective lens driving apparatus in which three lens drive coils are mounted on the lens holder so that focus control, tracking control, and tilt angle control of the objective lens can be performed.

  Conventionally known objective lens driving devices for general optical pickups have a lens holder on which an objective lens is mounted elastically supported by a support member via four conductive wires, and a moving coil system. In this case, one end of each of these four wires is connected to a focus coil and a tracking coil mounted on the lens holder (see, for example, Patent Document 1).

  FIG. 5 illustrates a conventional example disclosed in Patent Document 1 and the like. In the conventional objective lens driving apparatus shown in FIG. 5, the objective lens 1 facing the signal surface of the optical disk is mounted on a lens holder 2. The lens holder 2 is elastically supported by the support member 3 via four wires 4 made of a conductive metal material. A convex portion 3a is formed on the back surface side of the support member 3, and the central fixing portion 5a of the back substrate 5 is bonded and fixed to the flat surface of the convex portion 3a. The support member 3 is fixed on a base member (not shown).

  Both sides in the longitudinal direction of the central fixed portion 5a of the back substrate 5 are flexible portions 5b that are allowed to bend in the non-fixed region, and both the flexible portions 5b are opposed to the recessed step portions 3b of the support member 3. . The back substrate 5 has four conductive plate patterns made of elastic metal plates such as phosphor bronze arranged in non-contact with each other, and the four conductive plate patterns are sandwiched between heat-resistant insulating cover films such as polyimide films. It is a laminated substrate. Both flexible portions 5b of the back substrate 5 are provided with small holes that allow the wires 4 to pass therethrough in two places on the upper and lower portions, and a portion of the conductor plate pattern around each small hole. The land portion 6b is exposed. The center fixing portion 5a of the back substrate 5 is provided with external circuit connection lands 6a in which each conductive plate pattern is extended outward. These external circuit connection lands 6a are leads of a wiring board (not shown). Soldered to the pattern and connected to the external drive circuit.

  A focus coil C1 and a tracking coil C2 are mounted on the lens holder 2, and a magnetic path of a magnet (not shown) installed on the base member crosses the coils C1 and C2. Four wires 4 are installed on both side portions (ear portions 2a) of the lens holder 2, and one end portion of each wire 4 is connected to the focus coil C1 or the tracking coil C2. The other end portion of each wire 4 is soldered to the land portion 6 b through a damper material filling portion (not shown) of the support member 3 and the small hole of the back substrate 5.

  The objective lens driving apparatus schematically configured as described above is configured so that the drive current given from the external drive circuit to each conductor plate pattern via each external circuit connection land 6a is transmitted to each coil C1 via four wires 4. , C 2, the lens holder 2 is appropriately driven by electromagnetic force so that the posture of the objective lens 1 can be controlled in the focus direction and the tracking direction. Further, since the end of each wire 4 is soldered to a land portion 6b provided on the flexible portion 5b of the back substrate 5, it is possible to follow the bending deformation of each wire 4 when controlling the posture of the objective lens 1. The bending portion 5b can be elastically bent, and therefore it can be set so that higher-order resonance such as pitching operation does not adversely affect the focus control and tracking control.

  By the way, in recent years, an increase in the density of an optical disk has been promoted. However, when information is recorded on such a high-density optical disk, not only the focus control and tracking control of the objective lens mounted on the lens holder, but also this Tilt angle control is required to keep the optical axis of the objective lens substantially perpendicular to the signal surface of the optical disc.

  As a conventional example of an objective lens driving device that can perform focus control, tracking control, and tilt angle control of an objective lens in this way, six conductive wires are attached to three drive coils mounted on a lens holder. There is known one in which a drive current is supplied through the circuit (for example, see Patent Document 2).

In the conventional example disclosed in Patent Document 2, three wires are installed on both sides of a lens holder on which an objective lens and three drive coils are mounted, and one end of each wire has three lines. Connected to the drive coil. And although the lens holder is elastically supported through these six wires, it is not easy to attach the six wires in a well-balanced and high positional accuracy, and there is a concern about excessive restraint of the lens holder. About two of the six wires, the rigidity of the wire suspension is weakened by fixing the other end of the wire to the non-reinforcing region (region not supported by the reinforcing plate) of the flexible printed circuit board. This stabilizes and smoothes the operation of the lens holder when controlling the attitude of the objective lens.
Japanese Patent Laying-Open No. 2004-87037 (page 5-7, FIG. 1) JP 2004-145989 A (page 3-4, FIG. 1)

  As described above, the conventional objective lens driving apparatus that elastically supports the lens holder on which the objective lens and the three systems of driving coils are mounted via the six conductive wires is provided for two of the six. However, the rigidity of the wire suspension is reduced by fixing the end of the wire to the non-reinforcing region of the flexible printed circuit board. This non-reinforcing region is a narrow region facing the notch of the reinforcing plate. Since the allowable amount of bending is small, it is difficult to avoid that the operation of the lens holder is affected by the restraining force of the two wires. Further, since the remaining four wires have a structure in which the connecting portion is not easily elastically deformed, these four wires are likely to be a highly rigid wire suspension. Therefore, in such a conventional example, the lens holder is excessively restrained during the posture control of the objective lens and the smooth operation is hindered, or the operation of the lens holder becomes unstable due to the unbalance of the relative positions of the wires. It was difficult to solve the problem, and high reliability could not be expected.

  The present invention has been made in view of the situation of the prior art as described above, and an object of the present invention is to stabilize the lens holder with the wire suspension during the attitude control of the objective lens capable of focus control, tracking control and tilt angle control. It is an object of the present invention to provide an objective lens driving device that can be operated smoothly.

In the present invention, among the six conductive wires having one end connected to the three drive coils mounted on the lens holder, the other end of the four wires is a land in the non-fixed region of the back substrate. The other two ends of the remaining two wires are folded back to the side away from the lens holder with the flexible elastic protrusion provided in the non-fixed area so that the free end faces the back substrate. Then, it was decided to connect to the free end .

In the objective lens driving device of the present invention, two of the six wires laid on the lens holder have almost no function of supporting the lens holder, and the lens holder is effectively elasticated by the four wires. The objective lens is capable of focus control, tracking control, and tilt angle control even if it has a structure in which six wires of the same thickness are installed on the lens holder. It becomes easy to operate the lens holder stably and smoothly during posture control, and a highly reliable objective lens driving device can be provided at low cost. In addition, since the other ends of the two wires are folded back and connected to the free end of the elastic protruding piece to the side away from the lens holder, the longitudinal dimension of the wire that does not require the function of supporting the lens holder increases, And since these two wires are connected to the free end of the elastic projecting piece that is extremely flexible, the lens holder is hardly restrained by the wires when controlling the posture of the objective lens. Reliability is further improved.

The present invention is equipped with an objective lens facing the optical disc, three systems of drive coils for driving the objective lens in the optical axis direction, a direction orthogonal to the optical axis, and a tilt direction, and the objective lens and the drive coil. A lens holder, six conductive wires installed on both sides of the lens holder and having one end connected to the drive coil, and the other end of each wire connected. In an objective lens driving device comprising a flexible rear substrate and a support member to which a central portion of the rear substrate is fixed, and capable of focus control, tracking control, and tilt angle control of the objective lens with respect to the optical disc the elastic protruding pieces rich flexible than the other portion is provided in a part of both sides respectively except for the central portion of the rear substrate, or the elastic protruding pieces the lens holder Folded to the side away are opposed to its free end to the rear substrate, and the configuration of connecting the other end of the wire one by one out of the wire of each three lateral sides to the free end portion .

According to the objective lens driving device configured as described above, two of the six wires laid on the lens holder are connected to the elastic protruding piece with high flexibility provided in the non-fixed region of the back substrate. Therefore, these two wires have almost no function of supporting the lens holder, and the lens holder can be elastically supported by the four wires. Therefore, the objective lens driving device capable of focus control, tracking control, and tilt angle control can use six wires that do not require special processing and have the same thickness, and the lens holder is stable when controlling the attitude of the objective lens. In addition, the operation can be performed smoothly and the reliability can be improved.
In addition, since the other ends of the two wires are folded back and connected to the free end of the elastic protruding piece to the side away from the lens holder, the longitudinal dimension of the wire that does not require the function of supporting the lens holder increases, And since these two wires are connected to the free end of the elastic projecting piece that is extremely flexible, the lens holder is hardly restrained by the wires when controlling the posture of the objective lens. Reliability is further improved.

  In the above configuration, the back substrate has a laminate structure composed of six conductive plate patterns made of elastic metal plates arranged in parallel with each other and an insulating cover film sandwiching each of the conductive plate patterns. If the tip portions of the two conductor plate patterns out of the six pieces of the conductor plate patterns are projected from both side edges of the cover film to form the elastic projection pieces, the elasticity is extremely flexible. Since a protrusion piece can be formed easily, it is preferable.

  In this case, the two pieces of the conductive plate pattern are folded back toward the side away from the lens holder by the escape holes for loosely inserting the corresponding wires and the portions projecting from the both side edges of the cover film. The elastic projection piece is formed so that the portion faces the escape hole, and if the other end portion of the wire is connected to the free end portion of the elastic projection piece, the function of supporting the lens holder is achieved. Since the longitudinal dimension of the two wires which are not required increases and the wire is connected to the free end portion of the elastic projecting piece which is extremely flexible, these two wires are used when controlling the posture of the objective lens. The lens holder is hardly restrained by the wire, and the reliability is further improved.

  In the above configuration, when the other end portion of the wire located in the middle of the left and right sides is connected to the elastic protruding piece, the facing distance between the two wires on one side supporting the lens holder can be secured widely, Since it can support without inclination, it is preferable.

  The embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the objective lens driving device according to the embodiment, FIG. 2 is a plan view of the objective lens driving device, and FIG. 3 is a side view of the objective lens driving device. FIG. 4 is a perspective view of a rear substrate provided in the objective lens driving device, and parts corresponding to those in FIG.

  The objective lens driving device of the optical pickup shown in FIGS. 1 to 3 includes an objective lens 1 and a lens holder 2 equipped with three systems of driving coils C1 to C3, and four wires 4 and 2 made of a conductive metal material. The figure comprises a wire 8, a support member 3 fixed on a base member (not shown), and a back substrate 5 supported on the back side of the support member 3, and is installed on the base member. A magnetic path of a magnet (not shown) crosses each of the coils C1 to C3.

  The objective lens 1 is disposed so as to face the signal surface of the optical disk, and the objective lens 1 narrows down the laser light from a semiconductor laser (not shown) built in the base member, thereby signal surface (recording track) of the optical disk. And the return light reflected by the signal surface is collected and guided to the light receiving section. The lens holder 2 is equipped with two focus coils C1 and C3 and one tracking coil C2. By supplying a drive current to each of the coils C1 to C3 separately, the lens holder 2 is attached to the objective lens 1. Can be driven in the direction of the optical axis (focus direction), the direction orthogonal to the optical axis (tracking direction), and the tilt direction (tilt direction).

  Both the wire 4 and the wire 8 are conductive wires of the same thickness extending linearly, but the longitudinal dimension of the wire 8 is set slightly longer than that of the wire 4. Three of these wires 4 and 8 are installed on both side portions (ear portions 2 a) of the lens holder 2, and one wire 8 is disposed between the two upper and lower wires 4. One end of each wire 4, 8 is soldered to a relay substrate 9 attached to both sides of the lens holder 2, and one end of each wire 4, 8 is connected to the focus coil C 1 or the focus via this relay substrate 9. It is electrically connected to the coil C3 or the tracking coil C2. Although the detailed configuration is not shown, the other ends of the wires 4 and 8 extend through the recesses of the support member 3 to the back side, and a gel-like damper material is placed in the recesses. Filled.

  A convex portion 3a is formed on the back surface side of the support member 3, and the central fixing portion 5a of the back substrate 5 is bonded and fixed to the flat surface of the convex portion 3a. The non-fixed regions of the back substrate 5 located on both sides in the longitudinal direction of the central fixing portion 5a are flexible portions 5b that are allowed to bend. The flexible portions 5b are concave portions formed on the back surface of the support member 3. It faces the step 3b. Each flexible portion 5b is provided with a substantially L-shaped elastic protruding piece 6c, and the other end portion of the four wires 4 among the wires 4 and 8 extending to the back side of the support member 3. Are soldered to land portions 6b provided at a total of four locations, the upper and lower portions of each flexible portion 5b, while the other ends of the two wires 8 are soldered to the elastic protruding pieces 6c. ing.

  As shown in FIG. 4, the back substrate 5 has six pieces of conductive plate patterns 6 made of an elastic metal plate such as phosphor bronze arranged in non-contact with each other, and most of the six pieces of conductive plate patterns 6 are arranged. It is a substrate having a laminate structure sandwiched between heat-resistant insulating cover films 7 such as polyimide films. Each flexible portion 5b of the back substrate 5 is provided with two small holes 5c in the upper and lower portions, and a total of four small holes 5c through which the wire 4 passes, and the conductor plate pattern 6 is formed around each small hole 5c. A land portion 6b in which a part of the land is exposed is provided. In addition, the intermediate conductor plate pattern 6 that does not have the land portion 6b in each flexible portion 5b is provided with a relief hole 5d for loosely inserting the wire 8 with a diameter larger than that of the small hole 5c. A substantially L-shaped elastic protruding piece 6c is formed by folding a portion protruding from the cover film 7 to the side away from the lens holder 2 and having a free end facing the escape hole 5d. A small hole 6d through which the wire 8 passes is formed in the free end of 6c. That is, the wire 8 slightly longer than the wire 4 is loosely inserted into the escape hole 5d on the support member 3 side and penetrates the small hole 6d on the free end side of the elastic protruding piece 6c. The ends of the wires 8 are soldered to the elastic protruding pieces 6c. Further, the center fixing portion 5a of the back substrate 5 is provided with external circuit connection lands 6a in which the respective conductive plate patterns 6 are extended outwardly. These external circuit connection lands 6a are leads of a wiring board (not shown). Soldered to the pattern and electrically connected to the external drive circuit.

  The objective lens driving device configured as described above is configured so that the driving current supplied from the external driving circuit to each conductor plate pattern 6 via each external circuit connection land 6a is transmitted via each of the six wires 4 and 8. Since the power can be supplied to the coils C1, C2, and C3, the lens holder 2 is appropriately driven by electromagnetic force so that the posture of the objective lens 1 can be controlled in the focus direction, the tracking direction, and the tilt direction. In other words, focus control can be performed by supplying drive currents having the same magnitude and direction to the focus coils C1 and C3, and tilt angle control can be performed by supplying drive currents having different magnitudes and directions to the coils C1 and C3. . Further, tracking control can be performed by supplying a driving current to the tracking coil C2.

  Further, in the objective lens driving device according to the present embodiment, among the six wires 4 and 8 installed on the lens holder 2, the central two wires 8 are flexible portions 5 b that are non-fixed regions of the back substrate 5. The elastic protruding piece 6c is soldered to the free end of the elastic protruding piece 6c provided on the wire 8, but the elastic protruding piece 6c is more flexible in the longitudinal direction (tangential direction) of the wire 8 than the other flexible parts 5b. Since the wire 8 is longer than the other wires 4 and has a smaller spring constant, the two wires 8 soldered to the free end of the elastic protruding piece 6c have extremely high rigidity as a wire suspension. It is low. That is, these two wires 8 have almost no function of supporting the lens holder 2, and the lens holder 2 is substantially elastically supported only by the four wires 4. Further, since the end portion of each wire 4 is soldered to a land portion 6b provided on the flexible portion 5b of the back substrate 5, the rigidity of each wire 4 as a wire suspension does not become too high. Therefore, this objective lens driving device makes it easy to stably and smoothly operate the lens holder 2 on which the six wires 4 and 8 are laid during the attitude control of the objective lens 1, and it is easy to ensure high reliability. It has become. In addition, since the six wires 4 and 8 to be used do not need special processing and may have the same thickness, it is possible to suppress an increase in cost.

  In the present embodiment, out of the six wires 4 and 8, the two wires 8 positioned in the middle in the focus direction are connected to the elastic protruding piece 6c, so that the four wires mainly supporting the lens holder 2 are used. 4 can be arranged at intervals in the focus direction, and the lens holder 2 is not easily tilted (pitching or yawing). However, when the thickness dimension in the focus direction of the entire objective lens driving device can be ensured, the two wires 8 and the elastic protruding pieces 6c may be arranged at the upper end or the lower end.

It is a perspective view of the objective lens drive device concerning the example of the present invention. It is a top view of this objective lens drive device. It is a side view of this objective lens drive device. It is a perspective view of the back substrate with which the objective lens drive device is equipped. It is a perspective view of the objective lens drive device concerning a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Support member 4,8 Wire 5 Back substrate 5a Center fixed part 5b Flexible part (non-fixed area)
5d Escape hole 6 Conductor plate pattern 6a External circuit connection land 6b Land portion 6c Elastic protrusion 7 Cover film C1, C3 Focus coil C2 Tracking coil

Claims (4)

An objective lens facing the optical disc, three systems of driving coils for driving the objective lens in the optical axis direction, a direction orthogonal to the optical axis, and a tilting direction; a lens holder equipped with the objective lens and the driving coil; Three conductive wires are installed on both sides of the lens holder and one end of each lens holder is connected to the drive coil, and the other end of each wire is flexible. In an objective lens driving device comprising a rear substrate and a support member to which a central portion of the rear substrate is fixed, and capable of focus control, tracking control and tilt angle control of the objective lens with respect to the optical disc,
An elastic protruding piece that is more flexible than the other part is provided on each part of both sides except the central part of the back substrate, and the elastic protruding piece is folded back to the side away from the lens holder, and the free end part is An objective lens driving device characterized by facing the back substrate and connecting the other end of each of the three wires on the left and right sides to the free end .   2. The laminate according to claim 1, wherein the back substrate is composed of six conductive plate patterns made of elastic metal plates arranged in parallel with each other and an insulating cover film sandwiching the conductive plate patterns. The objective is characterized in that the elastic projecting piece is formed by projecting the tip end portions of the two conductor plate patterns out of the both side edges of the cover film among the six pieces of the conductor plate patterns. Lens drive device. 3. The escape hole for loosely inserting the corresponding wire into the two pieces of conductor plate patterns and the portions protruding from both side edges of the cover film are folded back to the side away from the lens holder. The elastic protruding piece is formed by making the free end portion formed opposite to the escape hole, and the other end portion of the wire is connected to the free end portion of the elastic protruding piece. Objective lens drive.   4. The objective lens driving device according to claim 1, wherein the other end portion of the wire located in the middle of the left and right sides is connected to the elastic protruding piece.

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