JPH0521334U - Drive coil attachment mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] In a drive coil attachment mechanism using a coil sheet body, which is formed by stacking insulating sheets having pattern coils formed thereon in multiple layers, as a drive coil, when the coil sheet body is attached to a holder, Make sure that the through holes that connect the pattern coils are not damaged. [Structure] Insulating sheets having pattern coils are laminated in multiple layers, and pattern coils are connected by through holes to form a coil sheet body 10. The coil sheet is formed on a holder 1 having a flat surface portion 14 and a coil. The sheet body 10 is attached, and the through hole is formed in the flat portion 14 of the holder 1.
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Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drive coil attachment mechanism such as an objective lens in an optical pickup.

[0002]

[Prior Art]

 An optical pickup used in an optical disc device or the like has an objective lens driving device for always focusing a light beam emitted from a laser device or the like on a predetermined recording track on the recording surface of the optical disc. The objective lens driving device consists of a focusing driving coil and a focusing magnet for driving the objective lens in the optical axis direction, and a tracking direction driving device for driving the objective lens in a direction orthogonal to the optical axis. And a drive device in the tracking direction, which includes a drive coil for tracking and a drive magnet for tracking.

The applicant has previously filed a patent for an objective lens driving device that is small, highly efficient, has a small number of components, is low in cost, and has high reliability. This is what is disclosed in Japanese Patent Application Laid-Open No. 1-307029, which is a focusing magnet and a tracking magnet, which are arranged on a continuous common surface and are magnetized by being divided in a direction orthogonal to each other. It has a focus drive coil and a tracking drive coil, which are arranged on a common continuous surface facing the magnet and the tracking magnet, respectively. The objective lens is moved in the direction of its optical axis by the thrust generated between the objective magnet and the objective lens is moved in the direction perpendicular to its optical axis by the thrust generated between the tracking magnet and the tracking drive coil. It is what you do.

According to the objective lens driving device according to the above application, the magnets are magnetized separately for focusing and tracking, and a dedicated magnetic circuit can be used for each magnet. Since the drive coil for tracking and the drive coil for tracking are arranged on the same plane, the magnetic gap in the part where each coil is located is small, and a high-density magnetic flux can be obtained, and an objective lens drive device with high efficiency can be obtained. Obtainable. In addition, since the focusing and tracking magnets, magnetic circuits, and coils can be designed as dedicated parts, performance can be improved by optimizing the design.

[0005]

[Problems to be solved by the device]

 As described above, the objective lens driving device according to the above application has excellent effects, but there is still room for improvement. In other words, the focus-only drive coil and the tracking-only drive coil are used as separate parts, and the winding coil is used, so that the assembly is complicated and the assembly cost is high. There were problems that the gap between the coil and the magnet could not be reduced, the sensitivity was low, the coil was prone to fraying due to overcurrent, and the reliability was low.

The present invention solves the above-mentioned problems of the prior art by using a coil sheet body in which insulating sheets having pattern coils are laminated in multiple layers as a drive coil, and at the same time, the coil sheet body is used as a holder. An object of the present invention is to provide a drive coil mounting mechanism that prevents damage to the through holes that connect the above-mentioned pattern coils of multiple layers when mounted.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is formed into a cylindrical shape by stacking insulating sheets having pattern coils formed thereon in multiple layers and connecting pattern coils with through holes to form a coil sheet body. In addition, the coil sheet body is attached to a holder having a flat surface portion, and the through hole is positioned on the flat surface portion of the holder.

[0008]

[Action]

 The coil sheet body, which is formed by stacking multiple layers of insulating sheets with pattern coils, bends according to the shape of the holder, causing a gap between the layers due to the radius difference between the inner and outer circumferences, and pulling force on the outer circumference. However, a shear force is also generated between the layers. However, since the coil sheet body is not bent in the plane portion of the holder, stress is not concentrated or shearing force is not generated in the through hole located in this plane portion.

[0009]

【Example】

 An embodiment of a drive coil mounting mechanism according to the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes an objective lens holder. The objective lens holder 1 is rotatable around a fixed shaft by inserting a shaft hole 7 into the fixed shaft and along the fixed shaft. It is movably supported. An objective lens 2 is attached to the objective lens holder 1 with its optical axis parallel to the shaft hole 7. A balancer 8 is attached to the objective lens holder 1 on the opposite side of the objective lens 2 around the shaft hole 7.

The objective lens holder 1 has sheet holding frames 20 and 20 which are symmetrical with respect to a line connecting the center of the shaft hole 7 and the center of the objective lens 2 and which are concentric with the shaft hole 7 and which are partially cylindrical. is doing. The balancer 8 is mounted between the sheet holding frames 20 and 20, and the back surface of the balancer 8 is a flat surface portion 14. On the outer peripheral surfaces of the sheet holding frames 20 and 20, a coil sheet body 10 in which a pattern coil 11 serving as a focus driving coil and a pattern coil 12 serving as a tracking driving coil are juxtaposed on an insulating sheet is attached by adhesion. Has been. The coil sheet body 10 has a length from one sheet holding frame 20 to the other sheet holding frame 20 via the flat surface portion 14 on the back surface of the balancer 8. The portion where the coil sheet body 10 is attached to the sheet holding frames 20 and 20 has a cylindrical shape along the partial cylindrical surface of the sheet holding frames 20 and 20, and the intermediate portion 13 in the longitudinal direction of the coil sheet body 10 is the above-mentioned plane. It is flat along the section 14. In FIG. 1, reference numeral 21 indicates a part of an adhesive agent for fixing the coil sheet body 10 to the sheet holding frame 20. In addition, a pressure-sensitive adhesive sheet obtained by polymerizing the above sheet body may be used together for adhesion.

Magnets 6, 6 are fixed by yokes 9, 9 on the outer peripheral side of the arc-shaped portion of the coil sheet body 10 along the arcs of the sheet holding frames 20, 20. The yokes 9 and 9 and the magnets 6 and 6 are formed in an arc shape concentric with the arc of the coil sheet body 10, and the inner peripheral surface of the magnets 6 and 6 and the outer peripheral surface of the arc portion of the coil sheet body 10 are defined. Are facing each other with a gap in between. The magnet 6 is integrally molded with, for example, a resin binder. As shown in FIG. 3, the magnet 6 is formed with a groove 6c in a direction parallel to the shaft hole 7 at an intermediate portion in the arc direction. The groove 6c serves as a boundary and the focusing magnet 6a and the tracking magnet 6a. It is divided into magnets 6b. The focus magnet 6a is divided and magnetized so that the N pole and the S pole are lined up in the axial direction, while the tracking magnet 6b is divided and magnetized in a direction orthogonal to the magnetization direction of the focusing magnet 6a. As a result, the N pole and the S pole are formed so as to be aligned in the circumferential direction. In this way, the magnets 6a, 6b are arranged on a continuous common surface by integral molding.

The focusing magnet 6 a of each magnet 6 faces the pattern coil 11 forming the focus drive coil of the coil sheet body 10, and the tracking magnet 6 b forms the tracking drive coil of the coil sheet body 10. It faces the pattern coil 12. The yokes 5, 5 are also fixed to the inner peripheral sides of the sheet holding frames 20, 20. The yokes 5 and 5 are formed integrally with the yokes 20 and 20, and the outer peripheries of the yokes 5 and 5 are formed into arcs concentric with the arcs of the yokes 20 and 20. As shown in FIGS. 2 and 5, through holes 23 are formed in the intermediate portion 13 of the coil sheet body 10 located on the flat portion 14 for connecting the pattern coils of the respective layers forming the coil sheet body 10. There is.

Next, an example of the coil sheet body 10 having the pattern coils 11 and 12 will be described with reference to FIG. In the example of FIG. 4, the coil sheet body 10 shows only the uppermost insulating sheet 10a. The insulating sheet 10a is formed by combining the pattern coils 11 and 11 forming the focus driving coil and the pattern coils 12 and 12 forming the tracking driving coil on one side and the other side with the middle portion 13 as a boundary by a method such as etching or plating. It is formed in a spiral shape. The pattern coils 11, 11 on one side and the other side are connected in series by the conductive pattern 11a for connection, and the pattern coils 12, 12 on one side and the other side are also connected in series by the conductive pattern 12a for connection. .. A predetermined number of the insulating sheets 10a are superposed and adhered to each other to form a single coil sheet body 10, and the terminals of the predetermined coil are connected by soldering or the like through a through hole to form each pattern of each insulating sheet. The coils 11 are connected in series, and similarly, the pattern coils 12 of each insulating sheet are connected in series. Note that these coils may be connected in parallel depending on the required specifications.

FIG. 6 shows an example of forming through holes for connecting the pattern coils formed on each insulating sheet. However, in the example of FIG. 6, it is composed of four insulating sheets 10a, 10b, 10c and 10d, and the pattern coil shows only the focusing pattern coil 11. In FIG. 6, two pattern coils 11 are formed for each of the insulating sheets 10a, 10b, 10c, and 10d, so that each of the pattern coils 11 is in series with each other through a through hole or on the same insulating sheet. Are connected through the routing pattern. The through hole for connecting each pattern coil 11 in series is composed of a through hole 22 for connecting between two adjacent insulating sheets and a through hole 23 for connecting between three adjacent insulating sheets. It Reference numeral 25 indicates a terminal for connecting the pattern coil 11 to an external circuit.

A pattern coil for tracking is formed on each of the insulating sheets 10a, 10b, 10c, and 10d in the same manner as in the example of FIG. 4, and a through hole for connecting each tracking pattern coil in series is formed. As in the case of the pattern coil 11, the through hole is formed, and the through hole that connects between two adjacent insulating sheets and the through hole that connects between three adjacent insulating sheets are formed. However, since it is the same as the focusing drive coil, its details are omitted.

The pattern coil of each layer can be electrically connected by enclosing a solder paste in each of the through holes 22 and 23 and performing a solder dip. Here, four insulating sheets are penetrated. Soldered in through holes. Such an insulation sheet itself and a coil sheet body in which a plurality of insulating sheets are laminated in multiple layers and the pattern coils of each layer are connected by through holes can be manufactured by using a known manufacturing method. The description of these manufacturing methods is omitted.

The coil sheet body 10 formed as described above is fixed along the sheet holding frames 20 and 20 of the objective lens holder 1 and the flat surface portion 14 therebetween as shown in FIG. However, among the through holes 22 and 23 described with reference to FIG. 6, the through hole 23 extending over the three insulating sheets is located on the flat surface portion 14 of the objective lens holder 1 as shown in FIGS. There is.

When the coil sheet body 10 is attached along the sheet holding frames 20, 20 and the flat surface portion 14 of the objective lens holder 1, the coil sheet body 10 is curved along the partial cylindrical surface of the sheet holding frames 20, 20. Assuming that the entire coil sheet body 10 is curved in a cylindrical shape as shown in FIG. 8, the through portions existing in all portions including the portions A and C near the both ends of the coil sheet body 10 and the central portion B are present. The stress due to bending concentrates on the holes. Therefore, as shown in FIG. 9, a crack 27 may occur in the soldering 24 in the through hole. Further, in the portions A and C near the both ends of the coil sheet body 10, a shearing force is generated as shown in FIG. 10 due to the displacement between the inner circumference side and the outer circumference side, and this shearing force causes soldering in the through hole 24. May cut along the shear plane 29. If a crack 27 is generated in the soldering 24 in the through hole or is broken by a shearing force, the sheet coil is disconnected between the insulating sheets.

The above-described problem due to the bending of the sheet body 10 is remarkable when the through holes are provided over a large number of insulating sheets, and to the extent that the through holes are provided over two insulating sheets. Almost no problem. However, in the example shown in FIG. 6, when the through hole 23 extending over the three insulating sheets is arranged in the central portion of the insulating sheet and the sheet body 10 is fixed to the objective lens holder 1, the through hole 23 becomes the objective lens. Since it is located on the flat surface portion 14 of the holder 1, the soldering in the through hole 23 is not damaged by stress concentration or shearing force due to bending of the sheet body 10. On the other hand, in FIG. 6, the through holes 22 that straddle the two insulating sheets are located at the curved portions on both sides of the insulating sheets, but the soldering inside the through holes 22 causes almost no damage as described above. Although it is not received, it may be positioned on the plane portion 14 if necessary.

The focusing operation and the tracking operation in the above-described embodiment are the same as those in the conventional optical pickup, and the description thereof will be omitted.

According to the embodiment described above, since the coil sheet body 10 in which the focusing pattern coil 11 and the tracking pattern coil 12 are juxtaposed on the insulating sheet is attached to the objective lens holder 1, the focusing drive coil is provided. Since it is not necessary to separately form the drive coil and the tracking drive coil one by one, assembly is easy and the assembly cost can be reduced, and the relative positional accuracy of the focus pattern coil and the tracking pattern coil is high. There is an effect. Moreover, unlike conventional coils, there is no fraying or peeling, so reliability is high, and because the sheet-shaped coil is easy to control the thickness, the gap of the magnetic path where the drive coil is located can be narrowed. Therefore, the driving sensitivity can be increased and the variation in the sensitivity can be reduced.

Further, since the through hole 23 extending over the three insulating sheets is located on the flat surface portion 14 of the objective lens holder 1, the soldering in the through hole 23 is performed by stress concentration and shearing force due to bending of the sheet body 10. The sheet coil is prevented from being damaged and the disconnection of the sheet coil between the insulating sheets can be prevented.

If possible, it is desirable to position all the through holes on the flat surface portion 14 of the holder. If this is not possible, as in the above embodiment, the through holes extending over more insulating sheets are located in the flat portion 14 of the holder.

The drive coil mounting mechanism according to the present invention can be applied not only to an optical pickup but also to a voice coil motor or other drive coil mounting mechanism for various applications.

[0025]

[Effect of the device]

 According to the present invention, since the sheet body in which the focus and tracking drive coils are juxtaposed on the insulating sheet is attached to the objective lens holder, it is not necessary to form the focus drive and tracking drive coils one by one. As a result, the assembly is easy, the assembly cost can be reduced, and the relative positional accuracy of the focusing and tracking drive coils is high. In addition, unlike conventional coils, there is no fraying or peeling, so reliability is high, and because the sheet-shaped coil is easy to control the thickness, it is possible to narrow the gap in the magnetic path where each drive coil is located. Therefore, the driving sensitivity can be increased and the variation in sensitivity can be reduced.

Further, since the pattern coils of the plurality of insulating sheets forming the coil sheet body are connected to each other by the through hole and the through hole is located on the flat surface portion of the holder, the through hole of the coil sheet body is formed. It is possible to prevent breakage of the sheet coil between the insulating sheets without being damaged by stress concentration due to bending and shearing force.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an objective lens driving device according to the present invention.

FIG. 2 is a left side view of the above embodiment.

FIG. 3 is a front view showing a magnet in the above embodiment.

FIG. 4 is a front view showing a specific example of a coil sheet body in the above embodiment.

FIG. 5 is a perspective view showing the external appearance of the above embodiment.

FIG. 6 is an exploded perspective view showing an example of a coil sheet body and its through holes that can be used in the present invention.

FIG. 7 is a plan view showing a curved state of a coil sheet body.

FIG. 8 is a plan view showing how a crack is generated in a through hole due to the bending of a coil sheet body.

FIG. 9 is a plan view showing how the through holes are damaged by the shearing force of the coil sheet body.

[Explanation of symbols]

 1 Holder 10 Coil Sheet Body 10a Insulating Sheet 10b Insulating Sheet 10c Insulating Sheet 10d Insulating Sheet 11 Focus Sheet Coil 12 Tracking Sheet Coil 22 Through Hole 23 Through Hole

Claims (1)

[Scope of utility model registration request] 1. A mounting structure of a driving coil which generates a driving force by a magnetic action and moves in a magnetic gap, wherein insulating sheets having pattern coils are laminated in multiple layers and through holes are provided between the pattern coils. A drive coil characterized in that the coil sheet body is connected to form a coil sheet body, the coil sheet body is attached to a holder which is formed in a cylindrical shape and has a flat surface portion, and the through hole is located in the flat surface portion of the holder. Attachment mechanism.