JP2013037739A - Lens device and optical pickup provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens drive device that converts the rotation of a lead screw to linear movement by use of a nut member, thereby moving a lens, the drive device being configured such that occurrence of a defective component is improbable and stable operation can be expected.SOLUTION: The lens drive device 40 has a return mechanism 60 that pushes a nut member 3, separated from a screw part 2a to a non-screw part 2b, back to the screw part 2a, thereby returning the nut member 3. The return mechanism 60 includes: a push back part 61 that has a portion abutting on the nut member 3 and moves relative to a base 101; an elastic part 62 that applies force opposite to the direction in which the nut member 3 helically engaged with the screw part 2a approaches the push back part 61; and a stopper part 63 fixed to the base 101 and used to limit the movement of the push-back part 61 caused by force applied by the elastic part 62.

Description

  The present invention relates to a lens driving device that uses a nut member to convert rotation of a lead screw into movement in a linear direction to move a lens. The present invention also relates to an optical pickup provided with such a lens driving device.

  Conventionally, for example, an optical device such as an optical pickup or a camera has been provided with a lens driving device that uses a nut member to convert the rotation of a lead screw into a linear motion to move the lens (for example, Patent Documents 1 to 3). 4). For example, in an optical pickup, this lens driving device is used for the purpose of correcting spherical aberration (see, for example, Patent Document 1).

  In the case where the lens driving device is provided in the optical pickup, for example, the collimating lens is moved by the lens driving device. By moving the position of the collimating lens in the optical axis direction, the convergence / divergence state of the light emitted from the collimating lens and incident on the objective lens is changed. For this reason, the spherical aberration can be corrected by driving the collimating lens by the lens driving device. The objective lens here is a lens that condenses the light emitted from the light source onto the information recording surface of the optical recording medium, and the collimating lens is disposed in the optical path between the light source and the objective lens.

JP 2009-117000 A JP 2007-287281 A JP 2007-232940 A JP 2002-287002 A

  FIG. 15 is a schematic perspective view showing the configuration of the lens driving device 100 included in the optical pickup developed by the applicant of the present invention. The lens drive device 100 for the optical pickup that has been developed in advance is provided on a base (not shown) constituting the optical pickup. In addition to the lens driving device 100, a light source, an optical member, a photodetector, an objective lens actuator, various circuit boards, and the like are attached to the base constituting the optical pickup.

  As shown in FIG. 15, the lens driving device 100 includes a stepping motor 1, a lead screw 2, a lead nut 3, a lens holder 4, a guide shaft 5, a pressurizing spring 6, and a return spring 7. Prepare.

  The stepping motor 1 is a drive source that rotates the lead screw 2. By using a stepping motor as a drive source, the amount of movement of the lens holder 4 that is moved by the rotation of the lead screw 2 can be managed by the number of steps. The lens driving device 100 includes a photo interrupter (not shown) that detects that the lens holder 4 is at the reference position. The position of the lens holder 4 can be grasped from the information from the photo interrupter and the number of steps of the stepping motor 1.

  A metal lead screw 2 attached to the output shaft of the stepping motor 1 is provided with a screw portion 2a in which a spiral screw is cut. It should be noted that there are non-threaded portions 2b in which the spiral screw is not cut on both ends of the lead screw 2. The non-screw portion 2 b may be a part of the lead screw 2 or a part of the output shaft of the motor 1. A plan view (assuming the case viewed along the X direction in FIG. 15), the resin lead nut 3 provided in a substantially cross shape has a through hole whose inner surface is threaded at a substantially central portion thereof. The lead screw 2 is screwed with the screw portion 2a. The lead nut 3 is disposed closer to the stepping motor 1 than the lens holder 4.

  The lead nut 3 is disposed such that the lower portion of the lead nut 3 engages with a guide groove (not shown) provided in a base constituting the optical pickup. For this reason, the lead nut 3 can move in the longitudinal direction of the lead screw 2 (X direction in FIG. 15) without rotating itself even when the lead screw 2 rotates.

  The lens holder 4 has a lens holding portion 4a that holds a collimating lens. Further, the lens holder 4 has an extending portion 4b extending from the lens holding portion 4a so as to be able to come into contact with the lead nut 3. The extending portion 4b is provided with a bearing portion 4c through which a guide shaft 5 disposed so as to be substantially parallel to the lead screw 2 is inserted. The guide shaft 5 inserted through the bearing portion 4 c is provided so as to be positioned closer to the lens holding portion 4 a than the lead screw 2.

  The lens holder 4 has a guide protrusion 4d that protrudes from the lens holding portion 4a to the opposite side to the extending portion 4b. As shown in FIG. 16, the guide protrusion 4d engages with a guide groove 8 provided in the base 110 (a member constituting the optical pickup). FIG. 16 is a schematic diagram showing the relationship between the guide projection 4d and the guide groove 8 in the lens driving device 100 provided in the optical pickup of the prior development.

  When the lens holder 4 is moved, the lens holder 4 is guided and moved by the guide shaft 5 inserted into the bearing portion 4c and the guide groove 8 engaged with the guide protrusion 4d. Note that the guide direction of the guide shaft 5 and the guide groove 8 coincides with the optical axis direction of the collimating lens held by the lens holder 4 (the X direction in FIG. 15 corresponds).

  A pressurizing spring (compression coil spring) 6 loosely fitted to the guide shaft 5 has one end abutting on the lens holder 4 and the other end abutting on a base constituting the optical pickup. The pressurizing spring 6 biases the lens holder 4 in a direction parallel to the optical axis direction of the collimating lens held by the lens holder 4 so that the lens holder 4 and the lead nut 3 come into contact with each other.

  When the lead nut 3 moves away from the stepping motor 1 by the rotation of the lead screw 2, the lens holder 4 is pushed by the lead nut 3. Thereby, the lens holder 4 moves in a direction away from the stepping motor 1 against the urging force of the pressurizing spring 6. On the other hand, when the lead nut 3 moves in a direction approaching the stepping motor 1, the lens holder 4 is pushed by the urging force of the pressurizing spring 6 and moves in a direction approaching the stepping motor 1 while contacting the lead nut 3.

  The return spring 7 is provided in order to prevent the lead nut 3 that moves in a direction approaching the stepping motor 1 from being disengaged (dropped off) from the threaded portion 2a of the lead screw 2 to the non-threaded portion 2b. The return spring 7 is obtained by bending a sheet metal.

  For example, when the control software for controlling the operation of the stepping motor 1 malfunctions, the operation in which the lead nut 3 approaches the stepping motor 1 may not stop. In such a case, the lead nut 3 is temporarily detached from the screw portion 2a of the lead screw 2, but can be returned to the screw portion 2a by the action of the return spring 7 when the control software returns to a normal state. . That is, the return spring 7 prevents the lead nut 3 from biting into (engaging with) the lead screw 2 even when the above-described malfunction occurs, and the lead nut 3 is not detached from the screw portion 2a of the lead screw 2. This prevents a situation where the screw part 2b is detached and cannot be used.

  By the way, the return spring 7 provided in the above-described lens driving device 100 has a complicated shape due to an influence such as a demand for miniaturization. FIG. 17 is a schematic side view of the return spring 7 included in the lens driving device 100 provided in the optical pickup developed by the present applicant. As shown in FIG. 17, the elastic portion 7a contacting the lead nut 3 of the return spring 7 is a portion bent at an acute angle with respect to the fixed portion 7b fixed to the base of the optical pickup, and is bent twice. Is a necessary configuration.

  Due to this complicated shape, the return spring 7 tends to vary in the direction indicated by the arrow D in FIG. 17 (corresponding to the X direction in FIG. 15). For example, when the elastic portion 7a has a shape that protrudes greatly toward the D1 side from the target shape, the lead nut 3 that moves in a direction approaching the stepping motor 1 cannot be removed from the screw portion 2a of the lead screw 2 to the non-screw portion 2b. The problem of biting into the screw portion 2a occurs. In addition, for example, when the elastic portion 7a has a shape that is contracted to the D2 side from the target shape, the return spring 7 cannot return the lead nut 3 that has been detached from the screw portion 2a to the non-screw portion 2b to the screw portion 2a. Will occur. That is, as a result of the above-described variation, the return spring 7 provided in the previously developed lens driving device 100 has a problem that the defect rate becomes high.

  In view of the above points, an object of the present invention is a lens driving device that moves a lens by converting rotation of a lead screw into a linear motion using a nut member, and it is difficult to generate defective parts and is stable. It is an object of the present invention to provide a lens driving device that can be expected to perform such operations. Another object of the present invention is to provide an optical pickup having such a lens driving device and having high reliability.

  In order to achieve the above object, the lens driving device of the present invention converts the rotation of the lead screw into a linear motion by a nut member screwed into the screw portion of the lead screw, and moves the lens relative to the base. A lens driving device, comprising: a return mechanism for returning the nut member released from the threaded portion to the non-threaded portion by pushing the nut member back to the threaded portion, wherein the return mechanism is a portion in contact with the nut member And a force applied in the direction opposite to the direction in which the nut member threadedly engaged with the screw portion approaches the push-back portion is applied to the push-back portion. A configuration (first configuration) is included that includes an elastic portion and a stopper portion that is fixedly disposed on the base and restricts the movement of the push-back portion due to the force applied from the elastic portion.

  According to this configuration, since the lens driving device has the return mechanism that returns the nut member that has come off from the screw portion to the non-screw portion to the screw portion, abnormality of the control software occurs. However, it can be expected that after the abnormality is resolved, the original state is restored and a stable operation is performed. In this configuration, the return mechanism includes a push-back portion, an elastic portion, and a stopper portion, and the return mechanism is not configured with only a leaf spring member. For this reason, it is avoided that the shape of the member (including the elastic member) required for the return mechanism is complicated, and it is difficult for a component defect to occur. Further, with this configuration, it is difficult for malfunctions in the return mechanism to occur.

  In the lens driving device having the first configuration, it is preferable that the stopper portion is configured to be provided integrally with the base (second configuration). In this configuration, it is easy to manage the dimensions of the stopper portion, and the malfunction of the return mechanism is further less likely to occur.

  In the lens driving devices having the first and second configurations, it is preferable that the elastic portion is a coil spring (third configuration). Coil springs tend to suppress variations in spring coefficient. For this reason, according to this configuration, it is easy to stabilize the operation of the return mechanism.

  In the lens driving device having any one of the first to third configurations, a motor that rotates the lead screw is provided, and the push-back portion has a plate shape that is substantially orthogonal to the longitudinal direction of the lead screw. The elastic portion may be configured (fourth configuration) between the motor and the push-back portion. According to this configuration, it is easy to make the configuration of the lens driving device a simple structure. Thereby, it is easy to ensure the operation performance of the lens driving device, and the assembling property of the lens driving device can be improved.

  In the lens driving device according to the fourth configuration, the elastic portion is a coil spring loosely fitted to the non-screw portion, and the motor has a first convex portion to which one end of the coil spring is attached. In addition, it is preferable that the push-back portion has a configuration (fifth configuration) in which a second convex portion to which the other end of the coil spring is attached is formed. According to this configuration, it is easy to stabilize the operation of the push-back portion by the coil spring.

  In the lens driving device according to any one of the first to third configurations, the return mechanism further includes a guide portion that is provided on the base and guides the pushing-back portion to move in the linear direction. The push-back portion includes a portion that abuts on the nut member and the stopper portion, and a first plate portion having a plate surface substantially orthogonal to the longitudinal direction of the lead screw, and substantially parallel to the longitudinal direction of the lead screw. It is preferable to adopt a configuration (sixth configuration) including a second plate portion that extends in the direction and engages with the guide portion. In this configuration, since the push-back portion can be obtained by simple bending of the sheet metal, it is difficult for component defects to occur.

  In the lens driving device having the sixth configuration, the second plate portion is formed with an opening that allows the hook portion protruding from the guide portion to protrude, and the hook portion engages with the guide portion. It is preferable that the second plate portion be configured to prevent the second plate portion from floating from the guide portion (seventh configuration). Thereby, the operation of the push-back portion can be stabilized, and the reliability regarding the operation of the lens driving device can be improved.

  In the lens driving device according to the sixth or seventh configuration, the elastic portion is attached to a first attachment portion having one end provided in the push-back portion and the second attachment portion provided in the base to the other end. It is preferable that the configuration is an extension spring (eighth configuration) attached to the frame. The tension spring is easy to suppress variations in the spring coefficient and is suitable as the elastic portion of the present invention. In addition, when a tension spring is used, the assembly operation of the lens driving device can be facilitated.

  In the lens driving device having the eighth configuration, the first mounting portion may be provided at a position higher than the second mounting portion with respect to the bottom surface of the base (ninth configuration). Good. Thereby, it is possible to reduce the possibility that the tension spring is detached due to an impact or the like, and it is difficult for the push-back portion to be lifted.

  In order to achieve the above object, the present invention is characterized in that it is an optical pickup including the lens driving device having any one of the first to ninth configurations. The optical pickup includes a light source, an objective lens that collects light emitted from the light source on an information recording surface of an optical recording medium, and a collimator lens disposed in an optical path between the light source and the objective lens. The position of the collimating lens may be moved by the lens driving device.

  According to the present invention, a lens driving device that moves a lens by converting rotation of a lead screw into a linear motion using a nut member, which is unlikely to generate defective parts and can be expected to operate stably. A device can be provided. Further, according to the present invention, it is possible to provide a highly reliable optical pickup provided with such a lens driving device.

1 is a schematic perspective view showing an external configuration of an optical pickup according to an embodiment of the present invention. 1 is a schematic plan view showing an optical configuration of an optical pickup according to an embodiment of the present invention. 1 is a schematic plan view illustrating a configuration of a lens driving device according to a first embodiment included in an optical pickup according to an embodiment of the present invention. 1 is a schematic perspective view showing a configuration of a pressing plate provided in the lens driving device of the first embodiment. Schematic plan view when the pressing plate and the stopper portion provided in the lens driving device of the first embodiment are viewed from the side where the lead nut is located The schematic side view for demonstrating the attachment structure of the coil spring with which the lens drive device of 1st Embodiment is provided. The schematic diagram for demonstrating the effect at the time of employ | adopting the lens drive device of 1st Embodiment. The graph for demonstrating the effect at the time of employ | adopting the lens drive device of 1st Embodiment. Schematic plan view showing the configuration of the lens driving device of the second embodiment The schematic perspective view which shows the structure of the return plate with which the lens drive device of 2nd Embodiment is equipped. The figure for demonstrating the structure of the part periphery in which the return mechanism is provided among the pickup bases with which the optical pickup of 2nd Embodiment is provided. Schematic cross-sectional view at the AA position in FIG. Schematic cross-sectional view at BB position in FIG. Schematic when the periphery of the tension spring provided in the lens driving device of the second embodiment is viewed from the side The schematic perspective view which shows the structure of the lens drive device with which the optical pick-up developed by the present applicant is equipped The schematic diagram which shows the relationship between a guide protrusion and a guide groove in the lens drive device with which the optical pick-up developed by the present applicant is equipped Schematic side view of a return spring included in a lens driving device provided in the optical pickup of the applicant's prior development

  Embodiments of an optical pickup to which the lens driving device of the present invention is applied will be described below with reference to the drawings. Note that the optical pickup according to the embodiment described below has information for three types of optical discs (an example of an optical recording medium) such as a Blu-ray disc (BD), a digital versatile disc (DVD), and a compact disc (CD). Can be read and written.

(Schematic configuration of optical pickup)
FIG. 1 is a schematic perspective view showing an external configuration of an optical pickup 10 according to an embodiment of the present invention. A pickup base 101 constituting the optical pickup 10 is mounted with a light source, an optical member, a lens driving device according to an embodiment of the present invention, an objective lens actuator, and a photodetector (which will be described later). Various circuit boards and wiring members (none of which are not shown) that are necessary for controlling the operation of the optical pickup 10 are also attached to the pickup base 101.

  Note that bearing portions 101 a and 101 b are provided at the left and right ends of the pickup base 101. The pickup base 101 is slidably supported by a bearing shaft 101a, 101b on a guide shaft (not shown) provided in an optical disk apparatus (an apparatus for reproducing or recording an optical disk). The optical pickup 10 slidably provided with respect to the guide shaft can read and write information by accessing a desired address of the rotating optical disk.

  FIG. 2 is a schematic plan view showing an optical configuration of the optical pickup 10 according to the embodiment of the present invention. The optical pickup 10 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. The optical path is formed. The optical pickup 10 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 10 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 10 can form an optical pickup corresponding to BD, DVD, and CD with a small number of parts.

  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). 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). That is, the second semiconductor laser 18 is configured to include two types of light sources. Such a laser light source can be constituted by, for example, a monolithic type or a hybrid type two-wavelength laser.

  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 (X direction in FIG. 2) by a lens driving device described in detail later. Then, the position of the collimating lens 15 is appropriately moved according to the change of the corresponding optical disc type, layer jump, or the like. The reason why the collimator lens 15 can be moved in this way is to adjust the degree of convergence / divergence of the light incident on the objective lenses 17 and 21 so as to appropriately suppress the influence of spherical aberration. For example, a BD is generally a multi-layer disc having a plurality of information recording surfaces in the thickness direction. For this reason, layer jump is generally performed in the case of BD correspondence, and it is necessary to appropriately correct spherical aberration at that time. The collimating lens 15 is an example of a lens that is moved by the lens driving device of the present invention.

  The first objective lens 17 and the second objective lens 21 are mounted on the pickup base 101 in a state where they are mounted on an objective lens actuator 30 (see FIG. 1) attached to the pickup base 101. The objective lens actuator 30 is a device that enables the two objective lenses 17 and 21 provided in the optical pickup 10 to move in the focus direction (applicable to the Z direction in FIG. 1) and the tracking direction (applicable to the Y direction in FIG. 1). is there.

  In the optical pickup 10, when information is read or written, it is necessary to perform focusing control so that the focal position of the first objective lens 17 (or the second objective lens 21) always matches the information recording surface of the optical disc. There is. Further, in the optical pickup 10, when reading and writing information, the position of the light spot condensed on the information recording surface of the optical disc by the first objective lens 17 (or the second objective lens 21) is It is necessary to perform tracking control so as to always follow the track of the optical disk. The objective lens actuator 30 is driven, for example, when performing these focusing control and tracking control.

  The objective lens actuator 30 has a lens holder 31 that holds the objective lenses 17 and 21, and is configured to support the lens holder 31 with a wire 32 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 objective lens actuator is known, detailed description thereof is omitted here.

(Configuration of lens driving device)
1. First Embodiment FIG. 3 is a schematic plan view showing a configuration of a lens driving device 40 of a first embodiment provided in an optical pickup 10 according to an embodiment of the present invention. The lens driving device 40 converts the rotation of the lead screw 2 into a linear motion by the lead nut 3 screwed to the screw portion 2a, and moves the collimating lens 15 in the optical axis direction (relative to the pickup base 101). Device). The lens driving device 40 provided on the pickup base 101 is generally built in the broken line region of FIG.

  The configuration of the lens driving device 40 of the first embodiment provided in the optical pickup 1 is substantially the same as the configuration of the lens driving device 100 (see, for example, FIG. 15) provided in the previously developed optical pickup described above. For this reason, in the lens driving device 40 of the first embodiment, the same reference numerals are given to portions where the configuration overlaps with the lens driving device 100 described above, and the description thereof is omitted unless particularly necessary. To do.

  The motor 1 provided in the lens driving device 40 is preferably a stepping motor, but may be a DC motor or the like depending on circumstances. When the motor 1 is a DC motor, the position of the lens holder 4 can be grasped by using an encoder, for example. The lead screw 2 having the screw portion 2a is an example of the lead screw of the present invention. Note that, as described above, the non-screw portion 2 b may be a part of the lead screw 2 or a part of the output shaft of the motor 1.

  The lead nut 3 is an example of the nut member of the present invention. In this embodiment, the lead nut 3 has a substantially cross shape in plan view (assumed to be viewed along the X direction in FIG. 3), but the shape can be changed as appropriate. In the lens driving device 40, the guide mechanism is formed using the guide shaft 5 and the guide groove 8 (provided in the pickup base 101). However, the lens driving device of the present invention is limited to this configuration. Is not to be done. Instead of the above-described configuration, for example, a configuration in which a guide mechanism is formed using two guide shafts may be employed.

  As shown in FIG. 3, the lens driving device 40 includes a return mechanism 60 that prevents the lead nut 3 from being unusable because the lead nut 3 is detached from the screw portion 2 a of the lead screw 2 to the non-screw portion 2 b. The return mechanism 60 is provided for the same purpose as the return spring 7 included in the lens driving device 100 described above, but its configuration is completely different. Hereinafter, the return mechanism 60 will be described.

  As shown in FIG. 3, the return mechanism 60 includes a plate-shaped pressing plate 61 disposed in the vicinity of the motor 1 and a coil spring disposed so as to be sandwiched between the motor 1 and the pressing plate 61 ( A compression coil spring) 62 and a columnar stopper portion 63 fixedly disposed on the pickup base 101. The coil spring 62 applies a force in the direction opposite to the direction in which the lead nut 3 approaches the pressing plate 61 to the pressing plate 61. Moreover, the stopper part 63 restrict | limits the movement (movement amount) of the return plate 61 which is going to move (relative movement with respect to the pick-up base 101) with the force provided from the coil spring 62. FIG.

  Note that the push-back plate 61 is an example of a push-back portion of the present invention. The coil spring 62 is an example of an elastic part of the present invention. Moreover, the stopper part 63 is an example of the stopper part of this invention.

  FIG. 4 is a schematic perspective view showing the configuration of the push-back plate 61 provided in the lens driving device 40 of the first embodiment. In FIG. 4A, the surface that contacts the lead nut 3 (hereinafter referred to as the front surface 61a) is mainly visible. In FIG. 4B, the back surface of the surface that contacts the lead nut 3 (hereinafter referred to as the front surface 61a). The rear surface 61b is mainly visible.

  As shown in FIG. 4, the push-back plate 61 has a substantially cross shape in plan view. A through hole that penetrates the front and rear surfaces 61a and 61b (plate surface of the push-back plate 61) is provided in the center portion of the push-back plate 61 so as to avoid interference with the screw portion 2a and the non-screw portion 2b of the lead screw 2. 611 is formed. A ring-shaped convex portion 612 is formed on the rear surface 61 b of the push-back plate 61 so as to surround the through hole 611. The pushing plate 61 can be formed of, for example, metal or resin. Further, the reason why the convex portion 612 is provided on the push-back plate 61 will be described later.

  As shown in FIG. 3, the push plate 61 has the lead screw 2 inserted through the through-hole 611, and its front and rear surfaces 61 a and 61 b are substantially orthogonal to the longitudinal direction of the lead screw 2 (X direction in FIG. 3). It is disposed in the vicinity of the motor 1 in a posture. The coil spring 62 is fitted to the lead screw 2 before the push-back plate 61 and is loosely fitted to the non-screw portion 2 b between the motor 1 and the push-back plate 61. In the present embodiment, the pair of stopper portions 63 that limit the movement of the push-back plate 61 biased by the coil spring 62 are provided integrally with the pickup base 101.

  FIG. 5 is a schematic plan view when the push-back plate 61 and the stopper portion 63 provided in the lens driving device 40 of the first embodiment are viewed from the side where the lead nut 3 is present. In FIG. 5, the broken line indicates the lead nut 3. As shown in FIG. 5, the push-back plate 61 can come into contact with the lead nut 3 on the center side. Further, the push-back plate 61 can come into contact with two stopper portions 63 on the left and right end sides thereof.

  In FIG. 5, reference numeral 1011 denotes a groove provided in the pickup base 101, and a part on the lower side of the lead nut 3 engages with the groove 1011. This prevents the lead nut 3 from rotating with the lead screw 2. Further, in the present embodiment, the shape of the push-back plate 61 is a substantially cross shape in plan view, but the shape is appropriately deformed within a range in which the contact between the lead nut 3 and the stopper portion 63 is ensured. I do not care. Further, in the present embodiment, the through hole 611 is provided in the push-back plate 61 in order to avoid interference with the lead screw 2. However, instead of the through hole 611, a cutout having a semi-cylindrical shape in plan view is pushed back. The structure provided in the plate 61 may be sufficient.

  FIG. 6 is a schematic side view for explaining an attachment configuration of the coil spring 62 provided in the lens driving device 40 of the first embodiment. In FIG. 6, the coil spring 62 is shown in a form as shown in a sectional view.

  As shown in FIG. 6, end windings 62 a that are closely wound are formed at both ends of the coil spring 62. One of the two end windings is fitted into the convex portion 1a so as to cover the outer surface of the columnar convex portion 1a (an example of the first convex portion of the present invention) formed in the motor 1. The other is fitted to the convex portion 612 so as to cover the outer surface of the convex portion 612 (an example of the second convex portion of the present invention) formed on the return plate 61. In addition, the convex part 1a formed in the motor 1 can be set as the structure which utilizes the convex part provided in the cover which covers the bearing with which the motor 1 is equipped, for example.

  The length l in FIG. 6 is the distance between the contact surface where one end of the coil spring 62 contacts the motor 1 and the contact surface where the other end of the coil spring 62 contacts the push-back plate 61 which contacts the stopper portion 63. Indicates. This length l is set shorter than the natural length of the coil spring 62. For this reason, the urging force from the coil spring 62 is always applied to the return plate 61.

  By attaching the coil spring 62 in this way, the center of rotation of the lead screw 2 (the output shaft of the motor 1) and the center of the coil spring 62 and the center of the through hole 611 of the push-back plate 61 are maintained in substantially the same state. Is possible. For this reason, the operation of the push-back plate 62 using the coil spring 62 becomes stable. In some cases, the coil spring 62 may be arranged without being fixed to the motor 1 and the pushback plate 61. Further, for example, the pickup base 101 may be provided with a rotation suppression mechanism (rotation suppression unit) that suppresses the rotation of the push-back plate 61.

  The effect of the return mechanism 60 comprised as mentioned above is demonstrated. First, as shown in FIG. 3, a state where the pushback plate 61 is not in contact with the lead nut 3 will be described. In this case, the return plate 61 receives a force in the direction opposite to the direction in which the lead nut 3 screwed into the screw portion 2a approaches the return plate 61 (rightward in FIG. 3) by the coil spring 62. However, since the stopper portion 63 exists, the pushing plate 61 is restricted in movement by the stopper portion 63 and remains in a fixed position.

  Next, a case will be described in which the lead nut 3 keeps moving in the direction approaching the stepping motor 1 due to, for example, malfunction of the control software. In this case, the lead nut 3 first comes into contact with the push-back plate 6. This contact occurs in a state where the lead nut 3 is screwed into the screw portion 2a. After that, the lead nut 3 tries to advance toward the side closer to the stepping motor 1, so that the push-back plate 61 also starts to move in the direction closer to the stepping motor 1.

  The lead nut 3 that advances while pushing the push-back plate 61 is detached from the screw portion 2a of the lead screw 2 to the non-screw portion 2b. At this time, the lead nut 3 receives a force in the direction opposite to the traveling direction from the push-back plate 61 pressed by the coil spring 62, but the lead nut 3 is adjusted by adjusting the elastic force of the coil spring 62. It comes off from the screw part 2a. This is to prevent biting (biting) between the screw portion 2 a of the lead screw 2 and the lead nut 3.

  While the abnormal state where the lead nut 3 continues to advance toward the stepping motor 1 is occurring, the lead nut 3 is detached from the screw portion 2a of the lead screw 2 and exists in the non-screw portion 2b. When the abnormal state is resolved, the lead nut 3 receives a force (restoring force) from the pushing plate 61 pressed by the coil spring 62 and is pushed to the screw portion 2a side. For this reason, when the lead nut 3 is rotated in a direction away from the stepping motor 1 to the lead screw 2, the lead nut 3 is engaged with (returned to) the screw portion 2a.

  FIG. 7 is a schematic diagram for explaining an effect when the lens driving device 40 of the first embodiment is employed. FIG. 7A is a view for explaining a case where the return mechanism 60 of the first embodiment is employed. FIG. 7B is a view for explaining the case where the above-described return spring 7 (see FIG. 15 and the like) is adopted as the return mechanism, and is a comparative view for easy understanding. In addition, description of the coil spring 62 is abbreviate | omitted in Fig.7 (a).

  As described above, the return spring 7 is likely to have manufacturing variations due to the complexity of its shape. That is, as shown in FIG. 7B, when the return spring 7 is used for the return mechanism, the distance L between the stepping motor 1 and the operating point at which the return spring 7 acts on the nut 3 and the return spring 7 varies. Likely to happen. In addition, the dashed-dotted line of FIG.7 (b) shows the state which the manufacture dispersion | variation in the return spring 7 produced. When the variation in the distance L is large, the lead nut 3 cannot be returned by the return mechanism, or the bite between the lead nut 3 and the lead screw 2 occurs.

  In this regard, in the return mechanism 60 of the present embodiment, the variation in the distance L between the stepping motor 1 and the operating point at which the return plate 61 acts on the lead nut 3 can be very small. This is because of the following two reasons. The first is that the push-back plate 61 has a simple plate shape, and the variation in the shape can be made very small. Secondly, the stopper portion 63 that determines the position of the action point of the push-back plate 61 is formed integrally with the pickup base 101 formed by resin molding, and its dimension management is easy to perform. It is done.

  FIG. 8 is a graph for explaining an effect when the lens driving device 40 of the first embodiment is employed. FIG. 8A is a graph when the return mechanism 60 of the first embodiment is employed. FIG. 8B is a graph when the above-described return spring 7 (see FIG. 15 and the like) is adopted as the return mechanism.

  In FIG. 8, the horizontal axis indicates the displacement of the spring, and the vertical axis indicates the spring force. A straight line K0 indicated by a solid line is a graph when the spring coefficient is substantially the same as the design value. A straight line K1 indicated by a broken line is a graph when the spring coefficient is deviated by about + 20% from the design value, and a straight line K2 indicated by a broken line is a graph when the spring coefficient is deviated by about −20% from the design value.

  In FIG. 8, the thick broken line indicates the design value (target value) of the spring displacement when the lead nut 3 falls out of the screw portion 2 a of the lead screw 2. The spring displacement when the lead nut 3 falls off includes, for example, variations in the operating point position of the return mechanism, variations in the thrust direction of the output shaft of the stepping motor 1 (same as the longitudinal direction of the lead screw 2), Variation due to thickness variation. The range indicated by the arrows in FIG. 8 indicates the range in which the spring displacement varies when the lead nut 3 falls off due to these variations.

  As described above, the variation in the operating point of the return mechanism is smaller in the return mechanism 60 of this embodiment than in the case where the return spring 7 is used as the return mechanism. For this reason, in FIG. 8A, the range in which the spring displacement varies when the lead nut 3 falls off is narrower than in FIG. 8B.

  The spring used in the return mechanism has a spring force exceeding a predetermined lower limit value (indicated by a two-dot chain line in FIG. 8) within a variation range indicated by an arrow in FIG. 8, and a predetermined upper limit value (in FIG. 8). It is required to be less than (shown by a two-dot difference line). Here, the predetermined lower limit value is the minimum force required to return the lead nut 3 to the screw portion 2a when the lead nut 3 is detached from the screw portion 2a of the lead screw 2. Further, the predetermined upper limit value is the maximum value of the thrust of the lead nut 3 generated by driving the stepping motor 1, and the lead nut 3 screwed into the screw portion 2a is detached from the screw portion 2a. It is a limit value. This maximum value is determined by the motor step-out limit.

  In the return spring 7 made of a leaf spring, the change in spring force with respect to the spring displacement tends to be large. Further, since the return spring 7 is likely to vary in its shape as described above, the variation in the spring coefficient tends to increase. As a result, as shown in FIG. 8B, the spring force may deviate from the limit value within the variation range indicated by the arrow. This is also related to the wide variation range indicated by the arrows.

  In this respect, since the return mechanism 60 of the present embodiment uses the coil spring 62, it is possible to suppress a change in the spring force with respect to the spring displacement. In addition, even if the spring coefficient of the coil spring 62 varies, it is possible to suppress a change in the relationship between the spring displacement and the spring force. Furthermore, in the return mechanism 60 of this embodiment, the range of variation indicated by the arrows can be suppressed to a small value. For this reason, as shown in FIG. 8A, the spring force does not deviate from the limit value within the variation range indicated by the arrows. That is, in the lens driving device 40 including the return mechanism 60, the return operation of the lead nut 3 detached from the screw portion 2a can be stably performed, and the biting between the lead nut 3 and the lead screw 2 may occur. Can be kept low.

  As described above, in the lens driving device 40 of the first embodiment, it is unlikely that the components constituting the return mechanism 60 will vary, and the return mechanism 60 can be expected to perform a stable operation. That is, it can be said that the optical pickup 10 including the lens driving device 40 of the first embodiment has high reliability in its operation. Further, since it is difficult for component defects to occur, cost reduction can be expected.

2. Second Embodiment Next, a lens driving device 40 according to a second embodiment will be described. In the lens driving device according to the first embodiment and the lens driving device according to the second embodiment, the return mechanism (the lead nut 3 is prevented from being unusable due to the screw portion 2a of the lead screw 2 being detached from the screw portion 2b). The structure of the mechanism is different, and the other parts are the same. Hereinafter, the description will focus on the return mechanism 50 provided in the lens driving device 40 of the second embodiment. In addition, the same code | symbol is attached | subjected and demonstrated about the part which overlaps with 1st Embodiment.

  FIG. 9 is a schematic plan view showing the configuration of the lens driving device 40 of the second embodiment. As shown in FIG. 9, the return mechanism 50 includes a turn-back plate 51 obtained by pressing a sheet metal. The return plate 51 has a portion that contacts the lead nut 3 and moves relative to the pickup base 101. The pressing plate 51 is an example of a pressing portion of the present invention. FIG. 10 is a schematic perspective view showing the configuration of the push-back plate 51 provided in the lens driving device 40 of the second embodiment. Details of the push-back plate 51 will be described with reference to FIGS. 9 and 10.

  The pushing plate 50 includes a first plate portion 511 having a plate surface substantially perpendicular to the longitudinal direction of the lead screw 2 (X direction in FIGS. 9 and 10). The first plate portion 511 includes a portion that comes into contact with the lead nut 3 approaching toward the stepping motor 1. As shown in FIG. 10, the first plate portion 511 is formed with a notch 511 a for avoiding interference with the lead screw 2. In addition, a bent portion 511b that is bent toward the stepping motor 1 side is formed on the upper portion of the first plate portion 511 in order to improve the strength.

  In addition, a first attachment portion 511c for attaching one end of the tension spring 52 is formed on the upper portion of the first plate portion 511 so as to be aligned with the bent portion 511b. The first mounting portion 511c is also obtained by bending a part of the upper portion of the first plate portion 511. The tension spring 52 applies a force in the direction opposite to the direction in which the lead nut 3 screwed into the screw portion 2a approaches the push-back plate 51 (rightward in FIG. 9). The tension spring 52 is an example of the elastic part of the present invention.

  The pushing plate 50 includes a second plate portion 512 that extends in a direction substantially parallel to the longitudinal direction of the lead screw 2. The second plate portion 512 is a portion that is bent to the side where the stepping motor 1 is not provided with respect to the first plate portion 511, and the bending angle with respect to the first plate portion 511 is approximately 90 °. The second plate portion 512 is provided near one end of the first plate portion 511 (in the Y direction in FIG. 10) in order to avoid interference with the lead screw 2.

  In order to avoid interference with the second plate portion 512, a notch (not shown) is formed in the end portion of the lens holder 4, and the configuration of the lens holder 4 is slightly changed from the configuration shown in FIG. Has been.

  Engagement walls 512a are formed at both ends of the second plate portion 512 in the short direction (Y direction in FIGS. 9 and 10) by bending the end portions downward. Due to the presence of the engagement wall 512a, the second plate portion 512 engages with a guide rail (details will be described later) provided on the pickup base 101.

  In addition, a grip portion 512b is formed at the distal end portion of the second plate portion 512 in the longitudinal direction (X direction in FIGS. 9 and 10) by bending a part of the end portion upward. This handle portion 512b is used as a handle for gripping the push-back plate 50 with tweezers or the like. The handle portion 512b may be omitted, but for the purpose of improving workability of the work for assembling the lens driving device 40, for example, the handle portion 512b is preferably provided as in the present embodiment.

  FIG. 11 is a diagram for explaining a configuration around a portion where the return mechanism 50 is provided in the pickup base 101 provided in the optical pickup 10 of the second embodiment. FIG. 11A is a diagram when the push-back plate 51 is not mounted on the pickup base 101, and FIG. 11B is a diagram when the push-back plate 51 is mounted on the pickup base 101. .

  In FIG. 11, a broken thick frame indicates a place where the stepping motor 1 is disposed. Further, reference numeral 1011 in FIG. 11 is an engagement groove that engages with the lead nut 3. By this engagement groove 1011, the lead nut 3 can move along the longitudinal direction (X direction) of the lead screw 2 without rotating itself even when the lead screw 2 rotates.

  As shown in FIG. 11, the pickup base 101 is provided with a pair of stopper portions 53 that are arranged symmetrically with the engagement groove 1011 in between the positions where the stepping motor 1 is arranged. The pair of stopper portions 53 is an example of the stopper portion of the present invention. The pair of stopper portions 53 are obtained by projecting part of the bottom surface of the base, and are provided integrally with the pickup base 101. The pair of stopper portions 53 abuts on the first plate portion 511 of the push-back plate 51 and restricts (regulates) the push-back plate 51 from moving in the direction away from the stepping motor 1.

  The pickup base 101 is provided with a guide rail 54 that extends in a direction parallel to the direction in which the engagement groove 1011 extends (the direction parallel to the longitudinal direction of the lead screw 2, the X direction). The guide rail 54 is obtained by projecting a part of the bottom surface of the base, and is provided integrally with the pickup base 101. The guide rail 54 is an example of a guide portion of the present invention.

  As shown in FIG. 12, the guide rail 54 is engaged with a second plate portion 512 that is substantially U-shaped in cross section due to the presence of the engagement wall 512a. The width (the length in the Y direction) and the height (the length in the Z direction) of the guide rail 54 are appropriately designed according to the size of the second plate portion 512. FIG. 12 is a schematic cross-sectional view at the AA position in FIG.

  FIG. 13 is a schematic cross-sectional view at the BB position in FIG. As shown in FIGS. 11 and 13, a hook portion 55 having a substantially L-shaped cross-sectional view (exactly, a shape in which the L shape faces sideways) protrudes from the upper surface of the guide rail 54. The hook portion 55 is provided near the end portion (end portion in the longitudinal direction) of the guide rail 54 on the side where the stepping motor 1 is disposed. The hook portion 55 is an example of the hook portion of the present invention.

  The second plate portion 512 of the push-back plate 51 is formed with an opening 512 c for projecting the hook portion 55 from the second plate portion 512 when the second plate portion 512 is engaged with the guide rail 54. Has been. The hook portion 55 protruding from the opening portion 512c has a function of pressing the second plate portion 512 that engages with the guide rail 54 from above, and the second plate portion 512 (push-back plate 51) is lifted from the guide rail 54. To prevent.

  Further, as shown in FIGS. 9 and 11, the pickup base 101 has a second attachment portion 56 for attaching the other end of the tension spring 52 whose one end is attached to the first attachment portion 511 c of the push-back plate 51. Is formed. FIG. 14 is a schematic view when the periphery of the tension spring 52 provided in the lens driving device 40 of the second embodiment is viewed from the side surface (along the Y direction). As shown in FIG. 14, the second mounting portion 56 has a hook shape in which the tip of the protruding portion protruding in the horizontal direction from the side wall of the pickup base 101 is bent downward.

  As shown in FIG. 14, the second attachment portion 56 is provided at a position lower than the first attachment portion 511 c provided on the return plate 51 with the bottom surface of the pickup base 101 as a reference. For this reason, the tension spring 52 having one end attached to the first attachment portion 511c and the other end attached to the second attachment portion 56 is inclined from the horizontal direction (inclined in the vertical direction).

  By the way, both ends of the tension spring 52 have a ring shape, and the attachment of the tension spring 52 is completed when the ring portion is hooked on the first attachment portion 511c and the second attachment portion 56. Since the tension spring 52 is disposed so as to be inclined in the vertical direction, an upward force is applied to the ring portion of the tension spring 52 in the second attachment portion 56. Therefore, the end portion of the tension spring 52 in which the ring portion is hooked on the second mounting portion 56 from the bottom to the top is difficult to come off from the second mounting portion 56.

  Further, since the tension spring 52 is disposed so as to be inclined in the vertical direction, a downward force is applied to the first mounting portion 511 c by the tension spring 52. For this reason, the push-back plate 51 is difficult to lift from the guide rail 54.

  The effect of the return mechanism 50 comprised as mentioned above is demonstrated. First, as shown in FIG. 9, a state where the pushback plate 51 is not in contact with the lead nut 3 will be described. In this case, the pushing plate 51 receives a force in the direction opposite to the direction in which the lead nut 3 screwed into the screw portion 2a approaches the pushing plate 51 (rightward in FIG. 9) by the tension spring 52. However, since the stopper portion 53 exists, the pushing plate 51 is restricted in movement by the stopper portion 53 and stays at a fixed position.

  Next, a case will be described in which the lead nut 3 keeps moving in the direction approaching the stepping motor 1 due to, for example, malfunction of the control software. In this case, the lead nut 3 first comes into contact with the first plate portion 511 of the push-back plate 51. This contact occurs in a state where the lead nut 3 is screwed into the screw portion 2a. After that, the lead nut 3 tries to advance toward the side closer to the stepping motor 1, so that the push-back plate 51 also starts moving in the direction approaching the stepping motor 1. At this time, since the second plate portion 512 is engaged with the guide rail 54, the pushing plate 51 moves in a direction substantially parallel to the longitudinal direction (X direction) of the lead screw 2.

  The lead nut 3 that advances while pushing the push-back plate 51 is detached from the screw portion 2a of the lead screw 2 to the non-screw portion 2b. At this time, the lead nut 3 receives a force in the direction opposite to the traveling direction from the push-back plate 51 pulled by the tension spring 52, but the lead nut 3 is adjusted by adjusting the elastic force of the tension spring 52. Is detached from the screw portion 2a. This is to prevent biting (biting) between the screw portion 2 a of the lead screw 2 and the lead nut 3.

  While the abnormal state where the lead nut 3 continues to advance toward the stepping motor 1 is occurring, the lead nut 3 is detached from the screw portion 2a of the lead screw 2 and exists in the non-screw portion 2b. When the abnormal state is resolved, the lead nut 3 receives a force (restoring force) from the pushing plate 51 pulled by the tension spring 52 and is pushed to the screw portion 2a side. For this reason, when the lead nut 3 is rotated in a direction away from the stepping motor 1 to the lead screw 2, the lead nut 3 is engaged with (returned to) the screw portion 2a.

  In the return mechanism 50 of the second embodiment, the distance L between the stepping motor 1 and the operating point at which the pushback plate 51 acts on the lead nut 3 (see FIG. 7A; reference numeral 61 is changed to 51 (511). , 63 can be replaced with 53). This is because of the following two reasons. The first is that the push-back plate 51 is formed only by simple bending (bending at approximately 90 °), and the variation in shape thereof can be made extremely small. Secondly, the stopper portion 53 that determines the position of the action point of the push-back plate 51 is formed integrally with the pickup base 101 formed by resin molding, and its dimension management is easy to perform. It is done.

  For this reason, also in the case of the return mechanism 50 provided in the lens driving device 40 of the second embodiment, the same effect as described in the above description using FIG. 8 is obtained. In the return mechanism 60 of the first embodiment, the spring is the compression coil spring 62, and in the return mechanism 50 of the second embodiment, the spring is the tension spring 52, but the difference in the difference is not significant.

  As described above, in the lens driving device 40 according to the second embodiment, it is difficult for the components constituting the return mechanism 50 to vary, and the return mechanism 50 can be expected to perform a stable operation. That is, it can be said that the optical pickup 10 including the lens driving device 40 of the second embodiment has high reliability in its operation. Further, since it is difficult for component defects to occur, cost reduction can be expected.

(Other)
The embodiment described above is an example of the present invention, and the scope of application of the present invention is not limited to the configuration of the embodiment described above.

  For example, in the lens driving device 40 according to the first embodiment described above, the compression coil spring 62 is an elastic portion that applies a force in a predetermined direction to the pressing plate 61. The coil spring 62 is merely an example of the elastic portion of the present invention, and other elastic members may be used. Moreover, in the lens drive device 40 of 2nd Embodiment, the structure which the elastic part which provides the force of a predetermined direction to the return plate 51 was the tension spring 52 was shown. The tension spring 52 is merely an example of the elastic portion of the present invention, and other elastic members may be used. In any of the embodiments, it is preferable to use a coil spring because it is easy to obtain a stable spring coefficient. The compression coil spring 62 of the first embodiment may be changed to a configuration using a tension spring, and the tension spring 52 of the second embodiment may be changed to a configuration using a compression coil spring. However, when making such a change, it is necessary to change the spring position from the position of the above-described embodiment.

  Further, in the lens driving device 40 of the second embodiment described above, the second plate portion 512 that constitutes the push-back plate 51 is bent to the side where the stepping motor 1 is not present with respect to the first plate portion 511. did. However, the present invention is not limited to this configuration, and the second plate portion 512 may be configured to be bent toward the side where the stepping motor 1 is present with respect to the first plate portion 511. When adopting this configuration, it is necessary to change the configuration position of the guide rail 54 and the like.

  In the embodiment described above, the pickup base 101 is the base constituting the lens driving device 40. However, the present invention is not limited to this configuration, and a base constituting the lens driving device 40 may be provided separately from the pickup base 101 and attached to the pickup base 101.

  In the embodiment described above, the stopper portion 53, the stopper portion 63, the guide rail (guide portion) 54, and the second attachment portion 56 are formed integrally with the pickup base 101. However, the present invention is not limited to this configuration, and at least one of these may be a separate member from the base.

  Further, in the embodiment described above, the return mechanisms 50 and 60 are configured to be applied to the end portion on the stepping motor 1 side (pointing to the end portion of the screw portion 2a of the lead screw 2). However, the scope of application of the present invention is not limited to this configuration. The present invention can also be applied to a case where a return mechanism is provided at the end opposite to the embodiment described above.

  In the embodiment described above, the case where the lens moved by the lens driving device 40 is the collimating lens 15 has been described. However, the application range of the present invention is not limited to this configuration, and the present invention can also be applied when other lenses are moved. For example, when a beam expander is used to correct spherical aberration, the lens driving device of the present invention can be applied to this. The lens driving device of the present invention is not limited to an optical pickup, and can be applied to other optical devices such as a camera.

  In the embodiment described above, the optical pickup 10 is configured to support BD, DVD, and CD. However, the present invention is applicable even when the type of optical disc that can be handled by the optical pickup is other than those shown in the above embodiments (including not only a plurality of types of optical discs that can be handled but also a single type). Naturally, it can be done.

  The lens driving device of the present invention is suitable for an optical device such as an optical pickup.

1 Stepping motor (motor)
1a Convex (first convex)
2 Lead screw 2a Threaded portion 2b Non-threaded portion 3 Lead nut (nut member)
10 optical pickup 11 first semiconductor laser (light source)
15 Collimating lens (lens)
17 First objective lens 18 Second semiconductor laser (light source)
21 Second objective lens 40 Lens driving device 50, 60 Return mechanism 51, 61 Reversing plate (reversing portion)
61a, 61b Plate surface 52 Tension spring (elastic part)
53, 63 Stopper 54 Guide rail (guide)
55 Hook part 56 Second attachment part 62 Coil spring (elastic part)
101 Pickup base (base)
511 1st plate part 511c 1st attaching part 512 2nd plate part 512c Opening part 612 Convex part (2nd convex part)

Claims (11)

A lens driving device that converts the rotation of the lead screw into a linear motion by a nut member that is screwed into the screw portion of the lead screw, and moves the lens relative to the base,
A return mechanism for returning the nut member released from the threaded portion to the non-threaded portion back to the threaded portion;
In the return mechanism,
A push-back portion that has a portion that contacts the nut member and moves relative to the base;
An elastic portion that applies a force in the direction opposite to the direction in which the nut member that is screwed to the screw portion approaches the push-back portion;
A stopper portion that is fixedly disposed on the base and restricts movement of the push-back portion due to a force applied from the elastic portion;
A lens driving device.   The lens driving device according to claim 1, wherein the stopper portion is provided integrally with the base.   The lens driving device according to claim 1, wherein the elastic portion is a coil spring. A motor for rotating the lead screw;
The push-back portion has a plate shape having a plate surface substantially orthogonal to the longitudinal direction of the lead screw,
The lens driving device according to claim 1, wherein the elastic portion is disposed between the motor and the push-back portion. The elastic portion is a coil spring that is loosely fitted to the non-screw portion,
The motor is formed with a first convex portion to which one end of the coil spring is attached,
The lens driving device according to claim 4, wherein a second convex portion to which the other end of the coil spring is attached is formed in the push-back portion. The return mechanism further includes a guide portion that is provided on the base and guides the return portion to move in the linear direction,
The pressing portion is
A first plate portion including a portion contacting the nut member and the stopper portion, and having a plate surface substantially orthogonal to the longitudinal direction of the lead screw;
A second plate portion extending in a direction substantially parallel to the longitudinal direction of the lead screw and engaged with the guide portion;
The lens driving device according to claim 1, comprising: The second plate portion is formed with an opening that allows the hook portion protruding from the guide portion to protrude,
The lens driving device according to claim 6, wherein the hook portion prevents the second plate portion engaged with the guide portion from floating from the guide portion.   8. The elastic part according to claim 6, wherein the elastic part is a tension spring attached at one end to a first attachment part provided at the push-back part and attached at the other end to a second attachment part provided at the base. The lens driving device described.   The lens driving device according to claim 8, wherein the first attachment portion is provided at a position higher than the second attachment portion with respect to the bottom surface of the base.   An optical pickup comprising the lens driving device according to claim 1. A light source;
An objective lens for condensing the light emitted from the light source on the information recording surface of the optical recording medium;
A collimating lens disposed in an optical path between the light source and the objective lens,
The optical pickup according to claim 10, wherein a position of the collimating lens is moved by the lens driving device.

Images