JP3097875U - Actuator for optical pickup - Google Patents

Abstract

An object of the present invention is to provide an optical pickup actuator that can reduce the manufacturing cost while maintaining a high drive efficiency of a lens holder.
An actuator holds a base (1) on which a support shaft (3) and a pair of permanent magnets (4) opposed to each other at a predetermined interval with the support shaft (3) interposed therebetween, and an objective lens (6). The permanent magnets 4 are supported on the support shaft 3 so as to be slidable in the axial direction and the circumferential direction, and the focusing coil 7 coaxially with the support shaft 3, and a pair of permanent magnets 4 facing each other. A lens holder 2 on which a tracking coil 8 is mounted, and a ring-shaped magnetic plate 10 is mounted coaxially with a lower end of the focusing coil 7. Further, a pair of magnetic pieces 10 a facing each of the permanent magnets 4 is attached to the inner periphery of the focusing coil 7, and each of the magnetic pieces 10 a is formed by bending the inner edge of the magnetic plate 10.
[Selection diagram] FIG.

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an optical pickup actuator mounted on an optical pickup device that reproduces and records information on an optical recording medium such as a CD, an MD, and a DVD.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an optical pickup actuator (hereinafter sometimes simply referred to as “actuator”), a lens holder holding an objective lens slides axially and circumferentially with respect to a support shaft fixed to a base. There is a so-called shaft sliding type which is supported as possible. In general, this type of actuator includes a focusing coil and a tracking coil fixed to the lens holder, and a lens on both sides of the lens holder so that the lens holder is driven by electromagnetic action to perform focusing and tracking on the objective lens. A pair of permanent magnets fixed to the base are provided, and by applying a current to the focusing coil, the lens holder moves along the support shaft to perform focusing, and the other applies a current to the tracking coil. This allows the lens holder to rotate around the support shaft to perform tracking (see, for example, Japanese Utility Model Registration No. 3088532 and JP-A-2003-59072).
[0003]
A conventional specific configuration of such an actuator will be described with reference to FIGS. FIG. 5 is a top view of a main part showing the appearance of a conventional actuator, FIG. 6 is a longitudinal sectional view showing a CC section of the actuator, and FIG. 7 is a longitudinal sectional view showing a DD section of the actuator. As shown in these drawings, the conventional actuator is mainly composed of a base 101 having ferromagnetism and a lens holder 102.
[0004]
The base 101 is fixed to a base member (not shown) on which a light emitting / receiving element or the like in the optical pickup device is mounted, and a column-shaped support shaft 103 is erected at the center thereof. Further, a pair of permanent magnets 104, 104 are provided on the base 101 in parallel with the support shaft 103 and opposed to each other at a predetermined interval so as to sandwich the support shaft 103. The lower ends of the permanent magnets 104, 104 are erected on the base 101 while their outer surfaces are magnetically attached to the auxiliary yoke portions 101a, 101a bent from both sides of the base 101. It is supported by the pin portions 101b, 101b.
[0005]
Further, on the base 101, a pair of main yoke members 105, 105 facing each of the permanent magnets 104, 104, which are located between the support shaft 103 and the permanent magnets 104, are provided upright. I have. Each of these main yoke members 105 is also a magnetic material having ferromagnetism. Here, each of the main yoke members 105, 105 effectively draws in the magnetic flux from each of the permanent magnets 104, 104, so that the main yoke members 105, 105 are mainly provided with a high-density focusing coil 107 and a tracking coil 108, which will be described later. And thereby enhances the driving efficiency of the lens holder 102.
[0006]
Subsequently, the lens holder 102 is formed by resin molding, and the objective lens 106 is held at one end portion 102a (the right portion in FIGS. 5 and 6). The center of the lower surface of the lens holder 102 is parallel to the optical axis direction of the objective lens 106 (the direction perpendicular to the paper plane in FIG. 5 and the vertical direction in FIG. 6) and has substantially the same diameter as the support shaft 103 of the base 101. Is formed, and an inner hole of the cylindrical portion 102b passes through the lens holder 102 itself. Further, a rectangular cylindrical portion 102c is formed on the lens holder 102 coaxially outside the cylindrical portion 102b, and the rectangular cylindrical portion 102c extends along both sides of the lens holder 102 (see FIG. 5 and FIG. 5). In FIG. 6, it is a left-right direction, and in FIG. 7, it is a short side and a long side perpendicular to the short side.
[0007]
Here, a focusing coil 107 is externally inserted into the rectangular cylindrical portion 102c. Both ends (upper and lower ends in FIGS. 6 and 7) of the focusing coil 107 are coaxially provided with a rectangular ring-shaped magnetic plate 109, 110 is also extrapolated. These are integrally fixed to the rectangular cylindrical portion 102c, that is, the lens holder 102, with an adhesive or the like. On both sides of the lens holder 102, which is outside the focusing coil 107, tracking coils 108, 108 are fixedly attached with an adhesive or the like. Further, between the cylindrical portion 102b and the short sides of the rectangular cylindrical portion 102c of the lens holder 102, through holes 102d, 102d having a size allowing the main yoke members 105, 105 of the base 101 are formed. ing.
[0008]
With such a configuration, the inner hole of the cylindrical portion 102b of the lens holder 102 is inserted into the support shaft 103 of the base 101, and the axis between the permanent magnets 104, 104 is The magnetic coils 109 and 110 and the permanent magnets 104 and 104 act as a magnetic attraction between the magnetic plates 109 and 110 and the permanent magnets 104 and 104, respectively. 108 is opposed to each of the permanent magnets 104, 104, and the lens holder 102 itself is maintained in a floating state. Thus, the focusing coil 107 and the tracking coil 108 are arranged between each of the permanent magnets 104, 104 and each of the main yoke members 105, 105, and a current is applied to the focusing coil 107 and the tracking coil 108. Then, the lens holder 102 is driven, so that focusing and tracking with respect to the objective lens 106 can be performed. The main yoke members 105 of the base 101 pass through the through holes 2d of the lens holder 102, and do not hinder the axial and circumferential movement of the lens holder 102.
[0009]
[Problems to be solved by the invention]
However, in the above-described conventional actuator, the main yoke members 105 and 105 are required to increase the driving efficiency of the lens holder 102, so that the number of components is large and the reduction in the manufacturing cost of the actuator itself is restricted. In addition, in the manufacturing stage in which the main yoke members 105, 105 are erected on the base 101, measures to prevent resonance of the main yoke members 105, 105 when the lens holder 102 is driven, for example, the main yoke is mounted on the base 101. Since the members 105 and 105 need to be firmly fixed with a plurality of screws or adhesives, as a result, the manufacturing cost has deteriorated.
[0010]
Therefore, the present invention has been made in view of the above problems, and has as its object to provide an optical pickup actuator that can reduce the manufacturing cost while maintaining the driving efficiency of the lens holder high.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an actuator according to the present invention includes a support shaft, a pair of permanent magnets facing each other at a predetermined interval with the support shaft interposed therebetween, and facing each other inside each of these permanent magnets. A base on which a pair of main yoke members are erected, and an objective lens are held, and the permanent magnets are supported slidably in the axial and circumferential directions on the support shaft between the permanent magnets. A focusing coil coaxial to an axis, and a lens holder to which a pair of tracking coils facing the respective permanent magnets are mounted outside the focusing coil, and upper and lower ends of the focusing coil In each of the optical pickup actuators having a ring-shaped magnetic plate mounted coaxially with the main yoke portion, the magnetic plate on the upper end side is eliminated. Instead, on the inner periphery of the focusing coil in the lens holder, a pair of magnetic pieces facing each of the permanent magnets is attached, and these magnetic pieces are separated from the inner edge of the magnetic plate on the lower end side. It is bent. Thereby, each magnetic piece fixed to the lens holder is magnetically paired with each permanent magnet fixed to the base, so that the driving efficiency of the lens holder during focusing and tracking on the objective lens can be increased. Therefore, each main yoke member required for the conventional actuator is not required at all, and as a result, the manufacturing cost of the actuator itself can be reduced.
[0012]
In addition, an actuator according to the present invention for achieving the above object includes a support having a support shaft, a base on which a pair of permanent magnets facing each other at a predetermined interval with the support shaft interposed therebetween, and an objective lens. Holding, slidably supported in the axial direction and circumferential direction on the support shaft between the permanent magnets, a lens holder having a focusing coil mounted coaxially with the support shaft, , A pair of magnetic pieces facing the respective permanent magnets is attached to the inner periphery of the focusing coil in the lens holder. Thereby, each magnetic piece fixed to the lens holder is magnetically paired with each permanent magnet fixed to the base, so that the driving efficiency of the lens holder during focusing on the objective lens can be increased. Therefore, each main yoke member required for the conventional actuator is not required at all, and as a result, the manufacturing cost of the actuator itself can be reduced.
[0013]
Here, for the purpose of obtaining a magnetic piece more easily, a ring-shaped magnetic plate is attached to the lower end of the focusing coil coaxially with the focusing coil, and each of the magnetic pieces is folded from the inner edge of the magnetic plate. Preferably, it is formed in a curved shape.
[0014]
Further, as a more practical configuration that functions as an actuator, it is preferable that a pair of tracking coils facing the respective permanent magnets is attached to the lens holder outside the focusing coil.
[0015]
[Embodiment of the invention]
Hereinafter, embodiments of the optical pickup actuator of the present invention will be described in detail with reference to the drawings. FIG. 1 is a top view of a main part showing an appearance of an actuator according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing an AA section of the actuator, and FIG. 3 is a longitudinal section showing a BB section of the actuator. FIG. 2 is a front view and an exploded perspective view showing an appearance of a lens holder in the actuator. In these figures, the same reference numerals are given to portions having the same name and performing the same function.
[0016]
As shown in FIGS. 1 to 4, the actuator of the present embodiment mainly includes a base 1 having ferromagnetism and a lens holder 2.
[0017]
The base 1 is fixed to a base member (not shown) on which a light receiving / emitting element, a half mirror, a prism, and the like in the optical pickup device are mounted, and a column-shaped support shaft 3 is erected at the center thereof. Have been. The base 1 is provided with a pair of permanent magnets 4, which are parallel to the support shaft 3 and face each other at a predetermined interval so as to sandwich the support shaft 3. The lower ends of the permanent magnets 4, 4 are erected on the base 1 while their outer surfaces are magnetically attached to the auxiliary yokes 1 a, 1 a bent from both sides of the base 1. It is supported by the pin portions 1b, 1b.
[0018]
Subsequently, the lens holder 2 is formed by resin molding, and the objective lens 6 is held at one end 2a (the right side in FIGS. 1 and 2). The center of the lower surface of the lens holder 2 is parallel to the optical axis direction of the objective lens 6 (the direction perpendicular to the paper plane in FIG. 1 and the vertical direction in FIG. 2) and has substantially the same diameter as the support shaft 3 of the base 1. Is formed, and an inner hole of the cylindrical portion 2b penetrates the lens holder 2 itself. Further, the lens holder 2 is formed with protrusions 2c extending in four directions from the outer periphery of the cylindrical portion 2b (see FIG. 4).
[0019]
Here, the focusing coil 7 is extrapolated to the four projections 2c with these four corners, and the lower end of both ends (upper and lower ends in FIGS. 2 and 3) is coaxially formed with the lower end. The rectangular ring-shaped magnetic plate 10 is also extrapolated. This magnetic plate 10 is also a magnetic material having ferromagnetism. These are further fixedly attached to the respective projections 2c, that is, the lens holder 2 with an adhesive or the like, and are integrally attached. Thus, the focusing coil 7 becomes coaxial with the cylindrical portion 2b. On both sides of the lens holder 2 outside the focusing coil 7 (upper and lower portions extending in the left-right direction in FIG. 1), the tracking coils 8, 8 are respectively fixed and attached with an adhesive or the like. ing.
[0020]
Further, the magnetic plate 10 is provided with magnetic pieces 10a, 10a bent from inner edges along both sides of the lens holder 2, and these magnetic pieces 10a, 10a are provided with the focusing coils 7a. Extends upward along the inner circumference of.
[0021]
With such a configuration, the inner hole of the cylindrical portion 2 b of the lens holder 2 is inserted into the support shaft 3 of the base 1, and the axis of the lens holder 2 is And the permanent magnets 4, 4 and the magnetic plate 10 including the magnetic pieces 10 a, 10 a, respectively. The tracking coils 8, 8 are opposed to the respective permanent magnets 4, 4, and the lens holder 2 itself is maintained in a floating state. Thus, the focusing coil 7 and the tracking coil 8 are arranged between each of the permanent magnets 4, 4 and each of the main yoke members 5, 5. Moreover, in that state, the magnetic pieces 10a, 10a face each other inside the permanent magnets 4, 4, and effectively draw in the magnetic flux from each of the permanent magnets 4, 4, and between them. A high-density magnetic flux is applied to the arranged focusing coil 7 and tracking coil 8, thereby serving to increase the driving efficiency of the lens holder 2. Therefore, the lens holder 2 is driven by applying a current to the focusing coil 7 and the tracking coil 8, thereby performing focusing and tracking on the objective lens 6.
[0022]
As described above, in the present embodiment, the magnetic pieces 10a, 10a fixed to the lens holder 2 are fixed to the base 1 instead of the main yoke members 105, 105 (see FIGS. 1 to 3) in the conventional actuator. Since it is magnetically paired with each of the permanent magnets 4 and 4, the driving efficiency of the lens holder 2 during focusing and tracking with respect to the objective lens can be kept high. Accordingly, the main yoke members 105, 105 which have been required in the past are not required at all, and as a result, the manufacturing cost of the actuator itself can be reduced. Moreover, the through holes 102d, 102d in the lens holder 102 for allowing the main yoke members 105, 105 are naturally unnecessary, and the production cost can be more effectively reduced.
[0023]
The present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention. For example, the projection 2c of the lens holder 2 may be replaced with a rectangular tubular portion 102c as in the related art. Further, each magnetic piece 10a, 10a may be a single component without being provided on the magnetic plate 10.
[0024]
[Effect of the invention]
As described above, according to the present invention, the support shaft, the pair of permanent magnets facing each other at a predetermined interval across the support shaft, and the pair of permanent magnets facing each The base on which the main yoke member is erected and the objective lens are held, and supported between the permanent magnets so as to be slidable on the support shaft in the axial direction and the circumferential direction, and on the support shaft. A focusing coil coaxially with the lens, and a lens holder to which a pair of tracking coils facing each of the permanent magnets is attached outside the focusing coil, and at upper and lower ends of the focusing coil, respectively. In an optical pickup actuator having a ring-shaped magnetic plate attached coaxially thereto, the magnetic plate on the upper end side is eliminated, and the lens is replaced with the main yoke member. A pair of magnetic pieces facing the respective permanent magnets are attached to the inner circumference of the focusing coil in the holder, and each of the magnetic pieces is formed by bending the inner edge of the magnetic plate on the lower end side. . Thereby, since each magnetic piece fixed to the lens holder is magnetically paired with each permanent magnet fixed to the base, it is possible to increase the driving efficiency of the lens holder during focusing and tracking with respect to the objective lens. . Therefore, each main yoke member required for the conventional actuator is not required at all, and as a result, the manufacturing cost of the actuator itself can be reduced.
[Brief description of the drawings]
FIG. 1 is a top view of a main part of an actuator according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 is a sectional view taken along line BB of FIG. 1;
FIG. 4 is an exploded perspective view of a lens holder in the actuator according to the embodiment of the present invention.
FIG. 5 is a top view of a main part of a conventional actuator.
FIG. 6 is a sectional view taken along the line CC of FIG. 5;
FIG. 7 is a sectional view taken along line DD of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base 1a Auxiliary yoke part 1b Pin part 2 Lens holder 2a One end part 2b Cylindrical part 2c Projection part 3 Support shaft 4 Permanent magnet 6 Objective lens 7 Focusing coil 8 Tracking coil 10 Magnetic plate 10a Magnetic piece

Claims (4)

A base on which a support shaft, a pair of permanent magnets facing each other at a predetermined interval across the support shaft, and a pair of main yoke members facing the inside of each of the permanent magnets Holding an objective lens, supported between the permanent magnets slidably in the axial direction and the circumferential direction on the support shaft, and a focusing coil coaxially with the support shaft; and A lens holder to which a pair of tracking coils facing the respective permanent magnets is attached outside the focusing coil, and a ring-shaped magnetic plate coaxially with the upper and lower ends of the focusing coil. In the actuator for the optical pickup to which is attached,
A pair of magnetic pieces facing each of the permanent magnets are attached to the inner periphery of the focusing coil in the lens holder, instead of removing the magnetic plate on the upper end side, instead of the main yoke member. Each of the magnetic pieces is bent from the inner edge of the magnetic plate on the lower end side. The support shaft, and a base on which a pair of permanent magnets facing each other at a predetermined interval with the support shaft interposed therebetween, and an objective lens are held, and the support shaft is provided between the permanent magnets. An optical pickup actuator comprising: a lens holder that is slidably supported in the axial direction and the circumferential direction and has a focusing coil mounted coaxially with the support shaft.
An actuator for an optical pickup, wherein a pair of magnetic pieces facing the respective permanent magnets is attached to an inner periphery of the focusing coil in the lens holder. A ring-shaped magnetic plate is attached to a lower end of the focusing coil coaxially with the lower end of the focusing coil, and each of the magnetic pieces is bent from an inner edge of the magnetic plate. The actuator for an optical pickup according to 1. The actuator for an optical pickup according to claim 2 or 3, wherein a pair of tracking coils facing the respective permanent magnets is attached to the lens holder outside the focusing coil.

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