JP2012252755A - Lens drive mechanism of optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive mechanism of an optical pickup at a low cost, preventing occurrence of malfunction.SOLUTION: A lens drive mechanism 40 includes a base 10, a motor 41, a lead screw 42, a nut member 43 screwed into a screw part 421 of the lead screw 42, lens holding member 44 for holding a lens (not shown in Figure) and moving with a movement of the nut member 43 by rotation of the lead screw 42, and a spring member 47 arranged near the end portion of the screw part 421 for giving a force in direction of pushing back to the nut member 43 which is approaching. The spring member 47 has a fixing part 471 to be fixed on the base 10 and an elastic part 472 which is a part folded to the fixing part 471 for giving a pushing back force to the nut member 43. A regulation wall 10h for regulating a projection amount from the fixing part 471 of the elastic part 472 is formed on the base 10.

Description

  The present invention relates to an optical pickup used for reading information recorded on an optical recording medium and writing information to the optical recording medium, and more particularly to a lens driving mechanism provided therein.

  Some conventional optical pickups include a lens driving mechanism that enables the lens to move in the optical axis direction so that spherical aberration can be corrected (see, for example, Patent Documents 1 to 4). As a specific example of this lens driving mechanism, for example, a collimating lens arranged in an optical system of an optical pickup can be moved in the optical axis direction (see, for example, Patent Document 1). When the position of the collimating lens is moved in the optical axis direction by the lens driving mechanism, the convergence / divergence state of the light emitted from the collimating lens and incident on the objective lens is changed, and the spherical aberration can be corrected. The objective lens here is a lens for condensing the light from the light source on the information recording surface of the optical recording medium.

  FIG. 9 is a schematic perspective view showing a configuration of a lens driving mechanism 100 of a conventional optical pickup. 10A and 10B are views for explaining a lead nut 103 provided in the lens driving mechanism 100 of the conventional optical pickup. FIG. 10A is a schematic perspective view of the lead nut 103, and FIG. It is a figure which shows the relationship of the lens holder 104. FIG.

  In the conventional lens driving mechanism 100 of the optical pickup, a lead screw 102 is attached to the output shaft of the stepping motor 101, and the lead screw 102 rotates by driving the stepping motor 101. The lead screw 102 is spirally threaded except for both ends.

  A lead nut 103 having a through hole 1031 (see FIG. 10A) with a threaded inner surface is screwed into the lead screw 102 (see FIG. 10B). The lead nut 103 has an engaging portion 1032 that engages with a guide rail provided on a base (not shown) on which the lens driving mechanism 100 is disposed (see FIG. 10A). As a result, the lead nut 103 moves along the guide rail without rotating itself even when the lead screw 102 rotates.

  The lead nut 103 is disposed closer to the stepping motor 101 than the lens holder 104 that holds the collimating lens. When the lead nut 103 moves away from the stepping motor 101 due to the rotation of the lead screw 102, the lens holder 104 is pushed by the lead nut 103.

  Two guide shafts 105 disposed substantially parallel to the lead screw 102 are inserted into the lens holder 104, and the lens holder 104 moves along the guide shaft 105. A pressure spring (coil spring) 106 is loosely fitted to one of the two guide shafts 105, and this pressure spring 106 biases the lens holder 104 toward the stepping motor 101.

  For this reason, when the lead screw 102 is rotated by driving the stepping motor 101 and the lead nut 103 moves away from the stepping motor 101, the lens holder 104 is pushed by the lead nut 103 and attached with the pressure spring 106. It moves in the direction away from the stepping motor 101 against the force. On the other hand, when the lead nut 103 moves in a direction approaching the stepping motor 101, the lens holder 104 moves in a direction approaching the stepping motor 101 by the biasing force of the pressurizing spring 106.

  The leaf spring member 108 is provided to prevent the lead nut 103 from falling off the thread of the lead screw 102 and the lead nut 103 becoming unusable. FIG. 11 is a schematic perspective view showing a configuration of a leaf spring member provided in a lens driving mechanism of a conventional optical pickup. The leaf spring member 108 includes a first portion 1081 serving as a top plate, a second portion 1082 that is bent with respect to the first portion 1081 and has a portion that comes into contact with the lead nut 103. And a fixing portion 1083 used for fixing to the base (the base on which the lens driving mechanism 100 is disposed). These parts are integrally formed.

  The fixing portion 1083 is provided at a position lower than the top plate, and has a plate surface substantially parallel to the top plate. On the plate surface substantially parallel to the top plate, there are formed screw holes 1083a formed so as to be able to fasten screws and positioning holes 1083b, 1083c formed so as to be positioned by positioning pins.

  FIG. 12 is a diagram for explaining a fixed state of a leaf spring member in a lens driving mechanism of a conventional optical pickup. As shown in FIG. 11, the leaf spring member 108 is located at the same position as the portion where the fixing portion 1011 provided in the stepping motor 101 is fixed to the base 200 (the base on which the lens driving mechanism 100 is disposed and the base of the optical pickup). Thus, the fixing portion 1083 is fixed.

  Specifically, the fixing portion 1011 (see also FIG. 9) of the stepping motor 101 is formed with a screw hole similar to the fixing portion 1083 of the leaf spring member 108 and two positioning holes. As a result, the two positioning pins 202 and 203 formed on the base 200 overlap the fixing portion 1011 of the stepping motor 101 and the fixing portion 1083 of the leaf spring member 108 (the direction of the fixing portion 1083 of the leaf spring member 108). Is positioned on the upper side). The fixing portion 1011 of the stepping motor 101 and the fixing portion 1083 of the leaf spring member 108 are fixed to the base 200 with screws 201.

  FIG. 13 is a diagram for explaining the action of the leaf spring member provided in the lens driving mechanism of the conventional optical pickup. As shown in FIG. 13, the leaf spring member 108 is disposed so as to contact the lead nut 103 in the vicinity of the screw end portion SE <b> 1 on the stepping motor 101 side of the lead screw 102. The leaf spring member 108 is elastically deformed when pressed by the lead nut 103 moving toward the stepping motor 101, and applies a force to the lead nut 103 toward the side where the other screw end SE2 is located. For this reason, the situation where the lead nut 103 falls off the thread of the lead screw 102 and cannot be used is prevented.

  The situation where the lead nut 103 continues to move away from the stepping motor 101 and falls off the thread of the lead screw 102 and cannot be used is not caused by the presence of the pressurizing spring 106.

JP 2009-277330 A JP 2009-117000 A JP 2010-211849 A JP 2008-41214 A

  However, the leaf spring member for preventing the lead nut from falling off the lead screw thread and becoming unusable tends to have a complicated shape and dimensional variations. As a result of this dimensional variation, the leaf spring member may interfere with other parts such as a lead screw. When such interference occurs, the lens driving mechanism may not operate normally, and the leaf spring member cannot be used. Therefore, there is a problem that the cost required for the lens driving mechanism increases.

  In view of the above points, an object of the present invention is to provide a low-cost lens drive mechanism for an optical pickup that is less prone to malfunction.

  In order to achieve the above object, the lens drive mechanism of the optical pickup of the present invention is arranged in an optical path between a light source and an objective lens that condenses light emitted from the light source on an information recording surface of an optical recording medium. A lens driving mechanism of an optical pickup for driving a lens to be driven, which includes a base, a motor mounted on the base, a lead screw that rotates by driving the motor, and a nut that is screwed into a screw portion of the lead screw A member, a lens holding member that holds the lens, and moves with the movement of the nut member by the rotation of the lead screw; and is disposed near the end of the screw portion and pushes back against the approaching nut member A spring member for applying a force in a direction, the spring member being fixed to the base, and a portion bent with respect to the fixed portion And an elastic portion that applies a force in the pushing-back direction to the nut member, and the base is formed with a restriction wall that restricts a protruding amount of the elastic portion from the fixed portion. This is a configuration (first configuration).

  The lens driving mechanism of this configuration is configured to include a spring member that pushes back the nut member in the vicinity of the end of the screw portion. For this reason, even if the nut member continues to move due to abnormal operation (such as malfunction of control software), it is difficult for the lead member and the nut member to bite, and the nut member can be removed from the screw portion of the lead screw. It can prevent a situation where it falls out and cannot be used. And the control wall which controls the protrusion amount from the fixing | fixed part (henceforth, component of a spring member) of an elastic part is provided in the base which can be formed with a small dimensional tolerance. For this reason, it is possible to prevent the elastic portion from interfering with the lead screw even if the manufacturing variation of the spring member (which causes malfunction) occurs. The spring member in which the variation causing the operation failure is normally handled as a defective product. However, according to this configuration, such a spring member can also be used, and the cost can be reduced.

  In the lens driving mechanism of the optical pickup having the first configuration, it is preferable that the restriction wall has a configuration (second configuration) which is a part of a wall of a space formed by cutting out the base. According to this configuration, it is easy to obtain the restriction wall even in a narrow space.

  In the lens drive mechanism of the optical pickup having the first or second configuration, the spring member may be arranged near the end of the screw portion on the motor side (third configuration).

  In the case of adopting the third configuration, it is preferable that the fixing portion of the spring member has a configuration (fourth configuration) in which a protrusion pressed by the motor is formed. According to this, the spring member can be fixed at its mounting position by being pressed by the motor (outer shell). For this reason, the fixing operation of the spring member is simplified. Further, in this configuration, the spring member can be fixed by the motor even if the motor does not include a fixing portion (referring to the one for fixing the motor itself), which is advantageous for cost reduction.

  In the lens driving mechanism of the optical pickup having any one of the first to fourth configurations, the base has a mounting portion into which the fixing portion of the spring member is inserted and arranged, and the spring member includes the mounting portion. It is preferable to have a structure having an engaging portion that functions as a retaining member from the mounting portion. According to this configuration, the spring member can be easily and reliably attached to the base, and the function of the spring member can be stably exhibited.

  According to the present invention, it is possible to provide a low-cost lens driving mechanism for an optical pickup that is unlikely to cause malfunction.

Schematic plan view showing the configuration of the optical pickup of the present embodiment Schematic plan view showing the optical configuration of the optical pickup of the present embodiment Schematic plan view showing the configuration of the lens driving mechanism provided in the optical pickup of the present embodiment Schematic perspective view showing the configuration of a return spring provided in the lens drive mechanism of the optical pickup of the present embodiment In the optical pickup of the present embodiment, a schematic perspective view showing a state in the middle of attaching a member constituting the lens driving mechanism to the pickup base In the optical pickup of the present embodiment, a schematic plan view showing a state in which the members constituting the lens driving mechanism have been attached to the pickup base Schematic cross-sectional view at position AA in FIG. Schematic diagram showing the state where the lead nut has moved from the state of FIG. 7 and is closest to the stepping motor. Schematic perspective view showing the configuration of a lens driving mechanism of a conventional optical pickup The figure for demonstrating the lead nut with which the lens drive mechanism of the conventional optical pick-up is equipped The schematic perspective view which shows the structure of the leaf | plate spring member with which the lens drive mechanism of the conventional optical pick-up is equipped. The figure for demonstrating the fixed state of the leaf | plate spring member in the lens drive mechanism of the conventional optical pick-up. The figure for demonstrating the effect | action of the leaf | plate spring member with which the lens drive mechanism of the conventional optical pick-up is equipped.

  Hereinafter, embodiments of an optical pickup to which the present invention is applied will be described with reference to the drawings. Note that the optical pickup of the present embodiment is configured to be able to read and write information on optical discs (an example of an optical recording medium) of three types of standards such as BD, DVD, and CD.

  FIG. 1 is a schematic plan view showing the configuration of the optical pickup of the present embodiment. When the optical pickup 1 shown in FIG. 1 reads information on the optical disk, the optical disk is disposed on the front side of the paper. In FIG. 1, a guide shaft GS that is not a component of the optical pickup 1 is also shown for easy understanding.

  As shown in FIG. 1, the optical pickup 1 includes a pickup base 10. An optical pickup 1 mounted in an optical disc device (device for reproducing and recording an optical disc) is slidably supported by two guide shafts GS arranged in the optical disc device. The desired address of the optical disc can be accessed by moving in the radial direction (radial direction) of the optical disc. Note that the pickup base 10 is supported by the guide shaft GS using bearings 10 a and 10 b provided at the left and right ends of the pickup base 10.

  Various members necessary for reading information recorded on the optical disk and writing information on the optical disk are mounted on the pickup base 10. The various members include semiconductor lasers 11 and 18 constituting a light source (see FIG. 2 to be described later), various optical members including objective lenses 17 and 21 (see FIG. 2 to be described later), a photodetector 23, and an objective lens. The printed circuit board 40 on which various circuits necessary for driving the actuators 30 for driving the motors 17 and 21 and the semiconductor lasers 11 and 18 and the actuators 30 are included.

  The semiconductor lasers 11 and 18 are attached to the pickup base 10 while being held by the holder. Most of the optical members are attached to the inside of the pickup base 10 from the back side (assuming that FIG. 1 is a view seen from the front side). The photodetector 23 is attached to the side surface of the pickup base 10.

  The actuator 30 is attached to the pickup base 10 such that the actuator 30 is entirely fitted in a recess 10 c provided in the pickup base 10. The objective lenses 17 and 21 mounted on the actuator 30 are exposed to the outside. The printed circuit board 40 is attached to the back side of the pickup base 10 so that the plate surface faces the back surface of the pickup base 10. In addition, a heat sink 50 made of a metal such as aluminum is attached to the pickup base 10 on the front side in order to dissipate heat generated by the semiconductor lasers 11 and 18.

  FIG. 2 is a schematic plan view showing the optical configuration of the optical pickup 1 of the present embodiment. The optical pickup 1 guides the light emitted from the first semiconductor laser 11 to the information recording surface of the optical disc and guides the reflected light (returned light) reflected from the information recording surface to the photodetector 23. An optical path is formed. The optical pickup 1 guides the light emitted from the second semiconductor laser 18 to the information recording surface of the optical disc, and guides the reflected light (returned light) reflected from the information recording surface to the photodetector 23. Optical paths for DVD and CD are formed.

  Note that the optical pickup 1 has a configuration in which a plurality of optical members are shared by the optical path for BD and the optical path for DVD and CD. Since such a configuration is adopted, the optical pickup 1 can form an optical pickup corresponding to BD, DVD, and CD with a small number of parts and can be miniaturized.

  First, the optical path for BD will be described. The first semiconductor laser 11 can emit BD laser light (for example, laser light having a wavelength of 405 nm band). The position at which the first semiconductor laser 11 is disposed corresponds to the position indicated by the broken line DL1 in FIG.

  Laser light emitted from the first semiconductor laser 11 is divided into main light and two sub-lights by the diffraction element 12. The laser beam that has passed through the diffraction element 12 is reflected by the polarization beam splitter 13 and passes through the quarter-wave plate 14 and the collimating lens 15. The laser light transmitted through the collimating lens 15 is reflected by the first rising mirror 16 and reaches the first objective lens 17 above the first rising mirror 16.

  The first objective lens 17 has a function of condensing incident laser light on the information recording surface of the optical disc. The laser beam condensed on the information recording surface by the first objective lens 17 is reflected by the information recording surface. This reflected light (returned light) passes through the first objective lens 17 and is reflected by the first rising mirror 16, and passes through the collimating lens 15, the quarter wavelength plate 14, the polarizing beam splitter 13, and the beam splitter 19. Transparent in order. Then, the return light transmitted through the beam splitter 19 is given astigmatism by the sensor lens 22 and is condensed on a predetermined light receiving region of the photodetector 23.

  The photodetector 23 functions as a photoelectric conversion unit that converts the received optical signal into an electrical signal. The electric signal output from the photodetector 23 is sent to a signal processing unit (not shown), and a reproduction signal, a focus error (FE) signal, a tracking error (TE) signal, and the like are generated by the signal processing unit.

  Next, optical paths for DVD and CD will be described. The second semiconductor laser 18 can emit by switching between laser light for DVD (for example, laser light having a wavelength of 650 nm band) and laser light for CD (for example, laser light having a wavelength of 780 nm band). Such a laser light source can be constituted by, for example, a monolithic type or a hybrid type two-wavelength laser. Note that the position where the second semiconductor laser 18 is disposed corresponds to the position indicated by the broken line DL2 in FIG.

  The laser light emitted from the second semiconductor laser 18 is reflected by the beam splitter 19, and then the polarizing beam splitter 13, the quarter wavelength plate 14, the collimating lens 15, and the first raising mirror 16 are sequentially arranged. To Penetrate. The laser beam that has passed through the first raising mirror 16 is reflected by the second raising mirror 20 and reaches the second objective lens 21 above the second raising mirror 20.

  The polarization beam splitter 13 is an optical member that acts on the BD laser beam, and the DVD laser beam and the CD laser beam are transmitted regardless of the polarization state. The first raising mirror 16 is a dichroic mirror, which reflects BD laser light but allows DVD laser light and CD laser light to pass therethrough.

  The second objective lens 21 has a function of condensing incident laser light on the information recording surface of the optical disc. The laser beam condensed on the information recording surface by the second objective lens 21 is reflected by the information recording surface. The reflected light (returned light) passes through the second objective lens 21 and is then reflected by the second rising mirror 20, and is reflected by the first rising mirror 16, the collimating lens 15, the quarter wavelength plate 14, and the polarized light. It passes through the beam splitter 13 and the beam splitter 19 in order. Then, the return light transmitted through the beam splitter 19 is given astigmatism by the sensor lens 22 and is condensed on a predetermined light receiving region of the photodetector 23.

  As in the case of BD compatibility, the electrical signal output from the photodetector 23 is sent to a signal processing unit (not shown), and a reproduction signal, an FE signal, a TE signal, and the like are generated by this signal processing unit.

  The collimating lens 15 can be moved in the optical axis direction (direction indicated by an arrow in FIG. 2) by a lens driving mechanism which will be described in detail later. The position of the collimating lens 15 is appropriately moved according to the type of optical disk, layer jump, and the like. The reason why the collimating lens 15 can be moved in this way is to adjust the degree of convergence / divergence of the laser light incident on the objective lenses 17 and 21 so as to appropriately suppress the influence of spherical aberration.

  Further, the first objective lens 17 and the second objective lens 21 are mounted on the pickup base 10 in a state where they are mounted on an actuator 30 (see FIG. 1) attached to the pickup base 10. The actuator 30 moves the two objective lenses 17 and 21 provided in the optical pickup 1 in a focus direction (in FIG. 1 and FIG. 2, a direction perpendicular to the paper surface) and a tracking direction (in FIG. 1 and FIG. It is a device that can be moved to the corresponding).

  In the optical pickup 1, when reading or writing information, it is necessary to perform focusing control so that the focal positions of the objective lenses 17 and 21 always match the information recording surface of the optical disc. Further, in the optical pickup 1, when reading or writing information, tracking is performed so that the position of the light spot condensed on the information recording surface of the optical disk by the objective lenses 17 and 21 always follows the track of the optical disk. It is necessary to control. The actuator 30 is driven, for example, when performing these focusing control and tracking control.

  The actuator 30 has a lens holder 31 (see FIG. 1) that holds the objective lenses 17 and 21, and is configured to support the lens holder 31 with a wire 32 (see FIG. 1) so as to be swingable. Then, the lens holder 31 (that is, the objective lenses 17 and 21) is moved by a force generated using a coil and a magnet. Since this type of actuator is known, a detailed description is omitted here.

  FIG. 3 is a schematic plan view showing the configuration of the lens driving mechanism 40 provided in the optical pickup 1 of the present embodiment. As shown in FIG. 3, the lens driving mechanism 40 of the optical pickup 1 includes the above-described pickup base 10, stepping motor 41, lead screw 42, lead nut 43, lens holder 44, guide shaft 45, A pressure spring 46 and a return spring 47 are provided.

  The pickup base 10 is an example of the base of the present invention. As another example, the base constituting the lens driving mechanism of the present invention may be a base dedicated to the lens driving mechanism 40, for example. In this case, a dedicated base on which each member constituting the lens driving mechanism 40 is mounted may be mounted on the pickup base 10.

  The stepping motor 41 is a drive source that rotates the lead screw 42 and is directly attached to the pickup base 10. By using a stepping motor as a drive source, the amount of movement of the lens holder 44 that moves as the lead screw 42 rotates (in other words, the amount of movement of the lens) can be managed by the number of steps. The lens driving mechanism 40 includes a photo interrupter (not shown) that detects that the lens holder 44 is at the reference position, and the position of the lens holder 44 is grasped together with information from the photo interrupter.

  The stepping motor 41 is an example of the motor of the present invention. As another example, a DC motor or the like may be employed. In this case, for example, an encoder or the like may be used to manage the movement amount of the lens.

  A metal lead screw 42 attached to the output shaft of the stepping motor 41 is provided with a screw portion 421 in which a spiral screw is cut. It should be noted that there are portions where the spiral screw is not cut on both ends of the lead screw 42.

  The resin-made lead nut 43 has a through-hole that is threaded on the inner surface, and is screwed into the screw portion 421 of the lead screw 42. The lower portion of the lead nut 43 is disposed so as to engage with a guide groove 10j (see FIGS. 5 and 7 described later) provided in the pickup base 10. For this reason, the lead nut 43 moves in the longitudinal direction of the lead screw 42 (the direction indicated by the arrow in FIG. 3) without rotating itself even when the lead screw 42 rotates.

  Note that the lead nut 43 is disposed closer to the stepping motor 41 than the lens holder 44. The lead nut 43 is an example of the nut member of the present invention. As shown in FIG. 5 to be described later, the lead nut 43 has a substantially cross shape in plan view, but it is needless to say that this shape may be changed as appropriate.

  The lens holder 44 includes a lens holding portion 441 that holds the collimating lens 15, and an extension portion 442 that extends from the lens holding portion 441 so as to be able to come into contact with the lead nut 43. In addition, the extending portion 442 is provided with a bearing portion 443 through which a guide shaft 45 disposed substantially parallel to the lead screw 42 is inserted. The lens holder 44 is an example of the lens holding member of the present invention.

  The longitudinal direction of the guide shaft 45 inserted through the bearing portion 443 is substantially parallel to the optical axis of the collimating lens 15 held by the lens holder 44. For example, both ends of the guide shaft 45 are fixed to the pickup base 10. In addition, a guide protrusion 44 a that protrudes in a direction substantially orthogonal to the optical axis direction of the collimator lens 15 held by the lens holder 44 is formed at the end of the lens holder 44 near the lens holding portion 441. The guide protrusion 44 a engages with a guide groove 10 e formed on the side wall 10 d constituting the pickup base 10. The guide groove 10 e extends in a direction substantially parallel to the optical axis of the collimator lens 15 held by the lens holder 44. The lens holder 44 is movable in the optical axis direction of the collimating lens 15 along the guide shaft 45 and the guide groove 10e.

  A pressurizing spring (coil spring) 46 loosely fitted to the guide shaft 45 has one end in contact with the lens holder 44 and the other end in contact with the side wall 10 f of the pickup base 10. The pressurizing spring 46 urges the lens holder 44 in a direction in which the lens holder 44 moving along the guide shaft 45 approaches the stepping motor 41.

  When the lead nut 43 moves away from the stepping motor 41 by the rotation of the lead screw 42, the lens holder 44 is pushed by the lead nut 43 and moves away from the stepping motor 41 against the biasing force of the pressurizing spring 46. Move to. On the other hand, when the lead nut 43 moves in a direction approaching the stepping motor 41, the lens holder 44 moves in a direction approaching the stepping motor 41 by the biasing force of the pressurizing spring 46.

  The return spring 47 is provided to prevent the lead nut 43 that moves in a direction approaching the stepping motor 41 from falling off the threaded portion 421 of the lead screw 42 and making the lead nut 43 unusable. Specifically, the return spring 47 is disposed in the vicinity of the end portion of the screw portion 421 on the stepping motor 41 side. The return spring 47 is elastically deformed when pressed by the lead nut 43 approaching the stepping motor 41 side, and gives a force in a direction to push back the approaching lead nut 43. For this reason, the situation where the lead nut 43 comes off from the screw part 421 of the lead screw 42 and cannot be used is prevented. The return spring 47 is an example of the spring member of the present invention.

  In the optical pickup 1 of the present embodiment, the lead nut 43 does not contact the return spring 47 during normal operation. For example, when the control software malfunctions during the operation of the stepping motor 41, the operation of the lead nut 43 approaching the stepping motor 41 may not stop. In such a case, the lead nut 43 contacts the return spring 47. Touch.

  When such a malfunction occurs, the lead nut 43 is temporarily detached from the screw portion 421 of the lead screw 42. However, when the control software returns to a normal state, the return spring 47 acts to the screw portion 421. Return. For this reason, in the configuration of the present embodiment, even when the above-described malfunction or the like occurs, the lead nut 43 comes off from the screw portion 421 of the lead screw 42 while preventing the lead nut 43 from biting into the lead screw 42. The situation where it becomes impossible to use can be prevented.

  FIG. 4 is a schematic perspective view showing the configuration of the return spring 47 provided in the lens driving mechanism 40 of the optical pickup 1 of the present embodiment. As shown in FIG. 4, the return spring 47 formed integrally with the sheet metal is fixed to the fixed portion 471 that is a portion used to fix and arrange the return spring 47 to the pickup base 10, and the fixed portion 471. An elastic portion 472 that is a bent portion and applies a force in a direction to push back the lead nut 43 approaching. A cutout 473 is formed in the fixed portion 471 and the elastic portion 472 so that the return spring 47 does not hit the lead screw 42.

  The fixing portion 471 has a first bent portion 471a obtained by bending the center of the bottom portion thereof to the side where the elastic portion 472 is not provided, and an upper portion of the left and right end portions thereof, respectively, bent toward the elastic portion 472 side. A second bent portion 471b having a substantially square shape is formed. As will be apparent from the description below, the first bent portion 471a is an example of the “projection portion pressed by the motor” of the present invention, and the second bent portion 471b is the “mounting portion of the present invention”. It is an example of an “engagement portion that functions as a stopper from falling out”.

  FIG. 5 is a schematic perspective view showing a state in the middle of attaching the members constituting the lens driving mechanism 40 to the pickup base 10 in the optical pickup 1 of the present embodiment. FIG. 6 is a schematic plan view showing a state in which the members constituting the lens driving mechanism 40 have been attached to the pickup base 10 in the optical pickup 1 of the present embodiment. 5 and 6 are partially enlarged views, and some parts are omitted. In FIG. 6, the pressurizing spring 46 is not shown. FIG. 6 shows a state where the lead nut 43 is not in contact with the return spring 47.

  When the lens driving mechanism 40 is attached to the pickup base 10, first, the fixing portion 471 of the return spring 47 (precisely, a part of the fixing portion 471 is attached) to the attachment portion 10 g provided integrally with the pickup base 10. ) Is inserted (state shown in FIG. 5). The mounting portion 10g is provided so as to sandwich the left and right end portions of the inserted return spring 47 from the front-rear direction. The expressions such as right and left and front and rear here are expressions in consideration of the state in which the return spring 47 is arranged as shown in FIG.

  When the return spring 47 is inserted into the mounting portion 10g, the second bent portion 471b that is provided in a substantially square shape and has elasticity is inserted into the mounting portion 10g (see FIG. 6). For this reason, the return spring 47 is not easily removed from the mounting portion 10g by the elastic force of the second bent portion 471b.

  When the return spring 47 is attached to the attachment portion 10g, the stepping motor 41 and the guide shaft 45 are then fixedly disposed on the pickup base 10. With these fixed arrangements, the lead screw 42, the lead nut 43, the lens holder 44, and the pressurizing spring 46 are also arranged on the pickup base 10.

  In the present embodiment, a screwing flange (for example, a fixed portion 1011 shown in FIG. 8 in the lens driving mechanism 100 of the conventional optical pickup) is separately attached to the stepping motor 41 for cost reduction. Not. For this purpose, the stepping motor 41 is fixed to the pickup base 10 using an adhesive.

  FIG. 7 is a schematic cross-sectional view at the position AA in FIG. As shown in FIG. 7, in a state where the stepping motor 41 is fixed to the pickup base 10, the first bent portion 471 a of the return spring 47 is pressed by the bearing portion 411 protruding from the main body portion of the stepping motor 41. It becomes a state. For this reason, the return spring 47 is difficult to come off from the mounting portion 10g.

  By the way, the elastic part 472 of the return spring 47 is a part obtained by being bent with respect to the fixed part 471, and the bending angle tends to vary. It is inconvenient if the elastic portion 472 of the return spring 47 interferes with the lead screw 42 due to this variation. For this reason, in the optical pickup 1 of the present embodiment, the following devices are provided.

  As shown in FIGS. 6 and 7, the pickup base 10 is formed with a regulation wall 10 h that regulates the protruding amount of the elastic portion 472 from the fixed portion 471. The restriction wall 10h is obtained by providing the pickup base 10 with a through hole 10i having a substantially rectangular shape (only an example) in plan view. Since the pickup base 10 is obtained, for example, by resin molding (the dimensional tolerance is small), the position of the restriction wall 10h can be a stable position.

  In the present embodiment, the through hole 10 i is connected to a guide groove 10 j provided for suppressing the rotation of the lead nut 43. However, since the width of the through hole 10i (the length in the vertical direction in FIG. 6 and the length in the direction perpendicular to the paper surface in FIG. 7) is wider than the width of the guide groove 10j, the restriction wall 10h is obtained. Yes.

  The return spring 47 is attached to the pickup base 10 in a state where the elastic portion 472 is elastically deformed so as to be accommodated in the through hole 10i (see FIG. 7). For this reason, the elastic portion 472 is attached to the pickup base 10 while receiving a force from the restriction wall 10h. In this configuration, even if the return spring 47 has the manufacturing variation as described above, the elastic portion 472 can be prevented from interfering with the lead screw 42. As a result, the yield of the return spring 47 can be improved and the cost can be reduced.

  FIG. 8 is a schematic diagram showing a state in which the lead nut 43 moves from the state of FIG. As described above, the lead nut 43 may be detached from the screw portion 421 of the lead screw 42 due to malfunction or the like. In this case, the elastic part 472 of the return spring 47 has the maximum deformation amount. As shown in FIG. 8, the through hole 10 i forming the regulation wall 10 h is provided so that the elastic portion 472 and the pickup base 10 do not interfere at this time.

  The embodiment described above is an example of the present invention, and the lens driving mechanism of the optical pickup of the present invention is not limited to the configuration described above.

  For example, in the embodiment described above, the regulation wall 10h that regulates the amount of protrusion of the elastic portion 472 from the fixed portion 471 (hereinafter referred to as a component of the return spring 47) has a through hole 10i formed by cutting out the pickup base 10. It was set as the structure which is a part of wall of (an example of the space part of this invention). However, the scope of the present invention is not limited to this configuration. That is, for example, the regulation wall that regulates the protruding amount of the elastic portion 472 from the fixed portion 471 may be a part of a wall of a recess (an example of the space portion of the present invention) formed by cutting out the pickup base 10. .

  Further, the restriction wall for restricting the protruding amount of the elastic portion 472 from the fixed portion 471 can be obtained by providing the protruding portion on the pickup base 10 if the space allows the pickup base 10 instead of notching the pickup base 10. There may be.

  In the embodiment described above, the nut member 43 is provided on the side where the stepping motor 41 is provided and the pressurizing spring 46 is provided on the side where the stepping motor 41 is not provided with the lens holder 44 as a reference. However, the present invention can also be applied to the case where the nut member 43 and the pressurizing spring 46 have an opposite positional relationship. In this case, the return spring 47 is disposed in the vicinity of the end portion of the screw portion 421 on the side where the stepping motor 41 is not provided.

  In the embodiment described above, the first bent portion 471a of the return spring 47 is pressed by the bearing portion 411 of the stepping motor 41. However, the present invention is not limited to this configuration. That is, a configuration in which the first bent portion 471a of the return spring 47 is pressed by the other outer shell portion of the stepping motor 41 is also included in the present invention.

  Moreover, in this embodiment shown above, it was set as the structure which also provided the 2nd bending part 471b in addition to the 1st bending part 471a so that the return spring 47 may not come off from the attachment part 10g. However, the present invention is not limited to this configuration, and a configuration in which the second bent portion 471b is not provided is also included in the scope of the present invention.

  In the present embodiment, the lens moved by the lens driving mechanism 40 is a collimating lens. However, the present invention is not limited to this, and the present invention can naturally be applied to a lens driving mechanism that moves other lenses. For example, the present invention can be applied to a lens driving mechanism that drives an expander lens used for correcting spherical aberration.

  Further, in the embodiment described above, the optical pickup is configured to support BD, DVD, and CD. However, the lens drive mechanism of the optical pickup according to the present invention is not limited to the type of optical disc that can be handled by the optical pickup other than those shown in the present embodiment (not only when there are a plurality of types of optical discs that can be handled, Of course, it is also applicable.

  The present invention provides an optical pickup provided with a lens driving mechanism that drives a lens disposed in an optical path between a light source and a condenser lens that condenses light emitted from the light source on an information recording surface of an optical recording medium. Is preferred.

1 Optical pickup 10 Pickup base (base)
10g Mounting part 10h Restriction wall 10i Through hole (space part)
11 First semiconductor laser (light source)
15 Collimating lens (lens)
17 First objective lens 18 Second semiconductor laser (light source)
19 Second objective lens 40 Lens drive mechanism 41 Stepping motor (motor)
42 Lead screw 43 Lead nut (nut member)
44 Lens holder (lens holding member)
47 Return spring (spring member)
411 Bearing portion 421 Screw portion 471 Fixing portion 471a First bent portion (protrusion portion)
471b Second bent part (engagement part)
472 Elastic part

Claims (5)

A lens driving mechanism for an optical pickup that drives a lens disposed in an optical path between a light source and an objective lens that focuses light emitted from the light source on an information recording surface of an optical recording medium,
Base and
A motor mounted on the base;
A lead screw that rotates by driving the motor;
A nut member screwed into the threaded portion of the lead screw;
A lens holding member that holds the lens and moves with movement of the nut member by rotation of the lead screw;
A spring member that is disposed near the end of the threaded portion and applies a force in a direction to push back against the nut member approaching;
With
The spring member has a fixed portion fixed to the base, and an elastic portion which is a portion bent with respect to the fixed portion and applies a force in the pushing back direction to the nut member,
A lens driving mechanism for an optical pickup, in which a restriction wall for restricting a protruding amount of the elastic part from the fixed part is formed on the base.   The lens driving mechanism of the optical pickup according to claim 1, wherein the restriction wall is a part of a wall of a space portion formed by cutting out the base.   The lens driving mechanism of the optical pickup according to claim 1, wherein the spring member is disposed in the vicinity of an end portion of the screw portion on the motor side.   The lens driving mechanism for an optical pickup according to claim 3, wherein a protrusion that is pressed by the motor is formed on the fixed portion of the spring member. The base has an attachment part into which the fixing part of the spring member is inserted and arranged,
5. The lens drive mechanism for an optical pickup according to claim 1, wherein the spring member has an engagement portion that engages with the attachment portion and functions as a retaining member from the attachment portion.

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