JP2928735B2 - Coil unit and optical pickup device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil unit and an optical pickup device using the same, and more particularly to a structure of a coil unit suitable for increasing the sensitivity and miniaturizing the optical pickup device.

[0002]

2. Description of the Related Art Conventionally, in a drive device for an optical recording medium such as a CD-ROM or a magneto-optical recording medium such as an MO disk, an optical pickup device for reading or writing information recorded on the disk is used. Is provided. This optical pickup device is provided with a movable unit containing a lens body supported movably in a focus direction and a tracking direction, and the movable unit is operated by a magnetic force of a drive coil to focus on a recording layer of a disk. And a tracking operation. This drive coil is used in
As disclosed in No. 023, a plurality of focus drive coils and a plurality of tracking drive coils are attached to the outer peripheral surface of the movable unit, and power supply wiring formed by a print power supply wiring layer or the like is attached to these drive coils. It is attached.

[0003]

However, in the conventional optical pickup device, after each drive coil is fixed on the outer peripheral surface of the movable unit, the power supply wiring is conductively connected to the winding end of the drive coil by solder or the like. Therefore, the manufacturing operation is complicated, and it is difficult to automate the assembling. Therefore, there is a problem that the mass productivity is low and the manufacturing cost is increased.

On the other hand, with the recent increase in density of recording media and the speed and miniaturization of drive devices, high sensitivity and miniaturization of optical pickup devices are also required.
In particular, recently, a quadruple speed optical pickup device has been required. However, conventionally, a circularly wound coil or a sheet coil is used as a driving coil, and the coil is occupied by an insulating film of a winding in a circularly wound coil and a multilayer structure for securing the number of turns in a sheet coil. As the product moment decreases and the thickness of each drive coil increases, there is a problem that it is difficult to achieve both high sensitivity and miniaturization.

It is an object of the present invention to provide a coil unit which has high mountability, can be made thinner, and has high magnetic characteristics. Another object of the present invention is to provide an optical pickup device with high sensitivity and reduced size.

[0006]

In order to achieve the above object, a coil unit according to the present invention comprises a flexible wiring board provided with a power supply wiring layer, a conductive thin film and an electric insulator layer of 2 to 6 μm alternately. And a slice thickness of 0.18 to which is fixed in a state where one end face is in contact with the substrate surface
A 0.30 mm ribbon coil, and a power supply wiring layer is conductively connected to a winding end of the ribbon coil.

[0007] Here, an exposed portion for connection of the power supply wiring layer is disposed directly below or inside the inner peripheral surface of the ribbon coil and directly below or outside the outer peripheral surface of the ribbon coil. It is preferable to conduct conductive connection between the inner peripheral surface and the outer peripheral surface using a conductive connection material.

It is preferable that the end surface of the ribbon coil is formed so as to conform to the shape of the mounting surface of the flexible wiring board.

Further, it is preferable that the flexible wiring board of the coil unit is mounted on a peripheral surface formed around the axis of the movable unit of the optical pickup device, and the thin coil of the coil unit is used as a driving coil of the movable unit. .

In this case, it is preferable to use a coil unit in which at least a pair of opposed or opposed thin ribbon coils are fixed on a peripheral surface formed around the axis of the movable unit of the optical pickup device.

[0011]

Therefore, according to the first aspect of the present invention, a ribbon coil having a slice thickness of 0.18 to 0.30 mm is fixed on a flexible wiring board, and 2 to 6 μm is provided between conductive films forming the coil. Since the electrical insulation layer is formed to electrically connect the power supply wiring layer and the winding end of the ribbon coil, the weight of the ribbon coil does not increase so much. The product moment is increased, the magnetomotive force is improved, and the connection work of the coil unit is facilitated.

According to the second aspect of the present invention, the inner peripheral surface or the outer peripheral surface of the ribbon coil is connected to the connecting exposed portion located immediately below, inside or outside the inner peripheral surface or the outer peripheral surface. Since the conductive connection is made by the material, an appropriate connection position is secured by placing the thin coil on the flexible wiring board.

Further, according to the third aspect of the present invention, since the end surface of the thin coil is formed so as to conform to the mounting surface shape of the flexible wiring board, when the thin coil is placed on the flexible wiring board, they are firmly engaged. .

According to the fourth aspect of the present invention, the coil unit according to any one of the first to third aspects is mounted by attaching a flexible wiring board to an outer peripheral surface of the movable unit of the optical pickup device. Do not increase weight. In addition, since the coil unit having the improved magnetomotive force is used, the movable unit moves greatly even if the voltage is slightly changed.

In addition, according to the invention of claim 5, one of the pair of ribbon coils can be used as a focus driving coil and the other can be used as a tracking driving coil.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of the coil unit of the present invention. This coil unit 10 is a flexible wiring board (FPC) in which a power supply wiring layer 12 made of a plurality of copper foils is formed on a base 11 made of a strip-shaped polyimide resin.
1, a pair of focus drive coils 31, 31 fixed on the flexible wiring board 1, and a pair of tracking drive coils 32, 32 similarly fixed. As shown in FIG. 2, the flexible wiring board 1 has a power supply wiring layer 12 formed by printing on a base 11, and a resist 13 covers the power supply wiring layer 12.

In the center of the flexible wiring board 1, FIG.
A terminal portion 1a having a narrow width as shown in FIG. 1 is formed, an end portion of the power supply wiring layer 12 is concentrated here, and a plurality of input pads 20 not covered with the resist 13 are formed.
Are formed. The other end of the power supply wiring layer 12 is
The resist 1 is disposed inside and outside the focusing drive coil 31 and the tracking drive coil 32, respectively.
The connection pads 21 and 22 which are not covered by the reference numeral 3 are formed.

Each of the focus driving coil 31 and the tracking driving coil 32 is constituted by a thin coil 33 as shown in FIG. The ribbon coil 33 is formed by coating one or both surfaces of a conductive film, for example, a metal foil 36 such as a copper foil with a resin electric insulator layer 38 and a resin adhesive layer 39, and winding this around a core jig. Turn to form a rod-shaped wound body. Here, the electric insulator layer 37 is composed of the resin electric insulator layer 38 and the resin adhesive layer 39. This wound body is completely adhered and solidified by heat or ultraviolet curing of the resin adhesive layer 39 in a firing step, and then, a strip coil is formed by removing the core jig and slicing the wound body. Is done.
Note that, in this embodiment, the resin electric insulator layer 38 is
6 is coated on only one side and the resin adhesive layer 39
Has insulation properties. After slicing, burrs are removed by etching or the like in order to prevent a short circuit at the coil end surface (cut).

In the thin coil 33, the thickness t1 of the metal foil 36 is usually set to about several tens of microns. On the other hand, the thickness t2a of the resin electric insulator layer 38 and the thickness t2 of the resin adhesive layer 39
2b, the thickness t2 of the electric insulator layer 37 is 2 to 6 .mu.m.
And In order to increase the space factor of the coil, it is necessary to reduce the thickness t2 of the electrical insulating layer 37, and to increase the number of turns, it is necessary to reduce the thickness t1 of the metal foil. However, if the thickness t2 of the electric insulator layer 37 is too small, the weight of the coil increases and the sensitivity when incorporated in the optical pickup device decreases. In addition, the insulation property deteriorates, and the magnetomotive force of the coil decreases. If the thickness t1 of the metal foil 36 is too small, the resistance increases and the magnetomotive force decreases. For this reason, in order to increase the sensitivity, predetermined t1, t
Must be a value of 2. In this embodiment, the metal foil 36 of the thin coil 33 used for the focus driving coil 31 is a copper foil, and its thickness t1 is 18 μm or 25 μm.
And On the other hand, a copper foil is also used for the metal foil 36 of the tracking drive coil 32, and the thickness t1 is 18 μm. In addition, a semi-curable insulating material having an adhesive function, for example, an epoxy resin, a rubber-modified epoxy resin, and imidazole were mixed (the mixing ratio was, for example, 70:30:45 or 50:50 in weight ratio). : 40, particularly preferably 70:30:45) When a resin is used as the insulating and bonding material, the thickness of the metal foil 36 is set to 16
Since a high-quality coil can be manufactured even when the thickness t2 of the electric insulator layer is suppressed to about 2 .mu.m, a high space factor of 80% or more can be obtained while securing a high number of turns.

In this case, as the manufacturing process, the metal foil 36
A step of coating each of the resin layers 38 and 39 above, a step of temporarily baking the coated metal foil 36 at about 80 to 150 ° C. to semi-harden the resin layers 38 and 39, and winding around a core jig. Step of forming a body, this wound body is 120 to 200
And a step of slicing the wound body. A high-density electrical insulator layer 38 of PAI (polyamide imide) resin having a thickness of about 1 μm is formed on one surface of the metal foil 36, and a semi-curing and insulating material is formed on one surface or the other surface of the metal foil 36. Resin adhesive layer 39 having a thickness of 1 μm.
By coating to a thickness of about m, it is possible to avoid insulation failure due to the occurrence of pinholes and the like while suppressing the thickness of the electric insulating material layer 38 and the resin adhesive layer 39. However, in this case, instead of the semi-curable resin, another insulating material having an insulating property may be used as long as the resin adhesive layer 39 can be made sufficiently thin. The resin adhesive layer 39 may be made of a thermoplastic resin such as a nylon-based, polyolefin-based, or esterimide resin, instead of a semi-curable resin, and a method of curing the wound body by a curing process.

[0022] The wound body formed in this way is 0.18 to
Slice to a thickness t of 0.30 mm. Then, the sliced ribbon coil 33 is attached to the flexible substrate 1 to form the focus drive coil 31 and the tracking drive coil 32. In this attachment, an electric insulating film 35 made of an epoxy resin, a phenol resin, or the like shown in FIG. 2 is formed on one or both end surfaces of the sliced ribbon coil 33. Next, the ribbon coil 33 is press-formed using a mold formed in accordance with the shape of the ribbon coil 33. This forming step is performed, for example, when the mounting surface of the focusing drive coil 31 and the tracking drive coil 32 is a curved surface, and the electric insulating film 35 of the thin coil 33 is formed.
Molding is performed so that the end face on which is attached has a similar curved surface. Each of the drive coils 31, 32 formed in this way
Has a slice thickness t of 0.18 to 0.30 mm.
The thickness t3 of the flexible wiring board 1 is 0.13 m.
m, and the thickness t4 of the entire coil unit is in the range of 0.30 to 0.45 mm.

When the wound body is sliced, it may be cut so that the end surface has the same shape as the mounting surface.

Finally, in accordance with the positions of the connection pads 21 and 22 formed on the surface of the flexible wiring board 1, the insulating film on the winding end surface existing on the inner and outer peripheral surfaces of the ribbon coil 33 is removed. By removing by a physical treatment such as polishing or a chemical treatment such as etching, the structure shown in FIG.
The driving coil 32 for tracking provided with the connection surface parts 32d and 32e shown in FIG. The focusing drive coil 31 is processed in the same manner, and the connection surface 31
d, 31e are formed.

The focus driving coil 31 and the tracking driving coil 32 formed in this manner are electrically insulated from the electric insulating film 3 corresponding to the positions of the connection pads 21 and 22.
5 is adhered with an adhesive or the like so that the end surface (the end surface formed into a shape that matches the mounting surface) is aligned with the surface of the flexible wiring board 1. At this time, as shown in FIG. 3, a holder 6 having a surface formed according to the shape of the mounting surface of the flexible wiring board 1 is prepared, and the flexible wiring board 1 is temporarily attached to the surface of the holder 6 with an adhesive or the like. If the end surfaces of the drive coils 31 and 32 are adhered to the surface of the temporarily attached substrate 1 in the attached state, the flexible wiring board 1 and the drive coils 31 and 32 can be securely fixed. In addition, the ribbon coil 33
Can be performed simultaneously with mounting on the flexible wiring board 1. That is, an adhesive is applied to the end face of the ribbon coil 33, and the end face to which the adhesive is applied is housed in the molding die 7 so as to be exposed. By pressing the ribbon coil 33 against the flexible wiring board 1, the ribbon coil 33 is pressed and adhered, and at the same time, the ribbon coil 33 is formed into a desired shape by being sandwiched between the molding die 7 and the surface of the flexible wiring board 1. You.

The connection surface portions 31d, 31e, 32d, 32e of the focus drive coil 31 and the tracking drive coil 32 fixed on the flexible wiring board 1 are:
As shown in FIGS. 1 and 2B, the connection pad 22 is located just above or inside the connection surface portion 32d, or just below the connection surface portion 32e, as shown in FIGS. Alternatively, they are arranged so that the connection pads 22 are located outside. Then, for example, the tracking drive coil 32 includes a connection surface portion 32d,
A conductive connection is made between the connection pad 32e and the connection pads 22 by a solder. This connection method is described in, for example, FIG.
As shown in FIG. 4, the cream solder 34 is supplied from the nozzle 8 having the outlet facing the connection surface portion 32e to the connection surface portion 32e and adhered thereto. Thereafter, as shown in FIG. Melts the solder solder 34 and flows down onto the connection pads 22 to form the connection surface 3
2e and the connection pad 22 are naturally connected. Here, a conductive paste such as silver wax can be used as the connection material. In this case, the conductive paste is applied to the connection surface portion 32.
d, 32e and the connection pads 22, 22, or are dropped from the nozzle 8. By doing so, the connection process can be automated and reliable conductive connection can be made, so that poor connection, disconnection accident, etc. can be prevented.

The coil unit 10 manufactured as described above comprises the thin ribbon coil 33 conductively connected to the flexible wiring board 1, so that the coil unit 10 can be made thinner than a conventional round coil or sheet coil. The number of turns can be ensured, and there is a remarkable effect that both miniaturization and high sensitivity of various devices can be achieved. When compared with a drive coil having the same drive performance, for example, a round wound coil has a thickness of 0.5 mm due to winding of a coated wire, and a sheet coil has a thickness of 0.5 mm to secure the number of turns.
It is necessary to laminate two to four layers of 22 mm, and in any case, a thickness of about 0.5 mm or more is required.
On the other hand, in the present embodiment, it is possible to realize a driving characteristic exceeding that of a round-wound coil or a sheet coil having the above-described dimensions even with a ribbon coil having a slice thickness of 0.2 mm as described later.

FIG. 5 is a schematic sectional view showing a state in which the coil unit 10 of this embodiment shown in FIG. 1 is applied to an optical pickup device of a CD-ROM drive. Here, the outer yoke plate 43, the inner yoke plate 44, and the support shaft 45 are integrated with each other, and the movable unit 4 supported by the support shaft 45 is supported.
Reference numeral 6 is attached so as to be movable in the axial direction of the support shaft 45 and to be rotatable around the axis. The movable unit 46 has a holding frame 47, and the objective lens 48 is accommodated in the holding frame 47. A pair of focusing magnets 49, 49 facing each other and a pair of similar tracking magnets 50, 50 are fixed to the inner peripheral surface of the outer yoke plate 43. The coil unit 10 includes a movable unit 46.
The drive coil 3 for focusing is adhered to the outer peripheral surface of the
Reference numerals 1 and 31 are arranged so as to face the focusing magnets 49 and 49, and the tracking driving coils 32 and 32 are arranged so as to face the tracking magnets 50 and 50, respectively. And each drive coil 31, 31, 32, 32
And the distance g between each magnet 49, 49, 50, 50 is
0.1 mm.

When the coil unit 10 is mounted on the optical pickup device shown in FIG. 5, the coil unit 10 is adhered and fixed in a state curved to the outer peripheral surface of the movable unit 46. The flexible wiring board 1 is connected to the connection portions of the coils 32, 32.
May be applied due to the deformation of the wire, disconnection of the connection portion, peeling of the coil, and the like may occur. Therefore, as described above, the fixed side end face of the ribbon coil is formed into a circumferential surface corresponding to the curvature of the outer peripheral surface of the movable unit 46 by press molding during coil manufacturing, so that the coil can be mounted on the movable unit 46. The accompanying disconnection, peeling, and the like can be prevented.

Each drive coil 3, which is a ribbon coil 33 formed in a shape conforming to the movable unit 46 in this manner,
1 and 32 are bonded to the flexible wiring board 1,
As shown in FIG. 6, the flexible wiring board 1 bends in accordance with the curvature of the end faces of the drive coils 31 and 32 due to flexibility. Does not occur. In addition, since the flexible wiring board 1 itself is bent in accordance with the deformation of the drive coils 31 and 32 as described above, the flexible wiring board 1 is particularly formed on a curved surface.
When attaching, the attaching operation becomes easy.

Next, the sensitivity of the optical pickup device incorporating this coil unit 10 and the sensitivities of our conventional product and comparative products (a) and (b) having slice thicknesses of 0.17 mm and 0.31 mm were determined. The results are shown in the following Table 1 and FIG. The hatched portion in FIG. 7 indicates a region that satisfies each sensitivity required for the quadruple-speed optical pickup device. Specifically, the sensitivity of the focus drive coil is 2
At 5 μm / V or more, the sensitivity of the tracking drive coil needs to be 17.5 μm / V or more.

[0032]

[Table 1] The other conditions from the product of the present invention and the comparative product (a) and (b) are as shown in Table 2 below.

[0033]

[Table 2]

The thickness t1 of the tracking drive coil 32 from the product of the present invention is 18 μm, and the thickness t1 of the focus drive coil 31 is 25 μm and 18 μm. In addition, each drive coil 3
The resistance values of 1, 32 are within the range of 6Ω ± 0.5Ω. As shown in Table 1 and FIG. 7, the optical pickup device incorporating the coil unit 10 of the present invention has a higher sensitivity than the applicant's conventional product, and can be applied to an optical pickup device for 4 × speed. It will be. In addition, the two sensitivities of the drive coils 31 and 32 are substantially equal, and the control is easy. In particular, both sensitivities are 1.3 times or more as compared with the conventional product of the applicant. In addition, the resistance value of each drive coil 31 and 32, each drive coil 31,
31, 32, 32 and each magnet 49, 49, 50, 5
Even if the interval g with 0 is changed by several tens of percent, the values are substantially the same. The slice thickness t of the drive coils 31 and 32 is from 0.12 to less than 0.18 mm and 0.30 mm.
Even if it exceeds 0.50 mm, the optical pickup device has higher sensitivity than the conventional product although it does not have the high effect of the product of the present invention. On the other hand, as shown in FIG. 8, the thickness t2 of the electric insulator layer is less than 2.0 μm, especially 1.
If the thickness is less than 75 μm, many pinholes are generated, and the withstand voltage value sharply decreases. Therefore, this thickness t2 is preferably set to 2 μm or more in consideration of safety. On the other hand, if the thickness t2 of the electrical insulator layer is too large, problems such as a decrease in the space factor of the ribbon coil and an increase in the size of the coil occur.

The above embodiment is one preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the space factor of the ribbon coil 33 (the volume ratio of the conductor)
In order to increase the number of turns, a semi-curing insulating resin layer having an adhesive function is applied to the conductive metal foil 36 as the thin coil 33, and the coil is manufactured by winding it. It will be preferable. Further, it is desirable to form an electrically insulating film on both end surfaces of the ribbon coil in order to secure insulation. When the resin adhesive layer 39 has no electric insulation, only the resin electric insulation layer 38 needs to have a thickness of 2 to 6 μm.

In the conductive connection step, a step of applying a conductive heat-flowable material such as cream solder to the inner and outer peripheral surfaces of the ribbon coil is performed. It is more desirable to form the conductive coil between the inner and outer peripheral surfaces of the ribbon coil and the exposed portion for connection.

The peripheral surface formed around the axis of the movable unit 46 refers to the outer peripheral surface of the movable unit 46 itself,
This includes the case of the inner peripheral surface of the member surrounding the movable unit 46. Then, when the outer peripheral surface of the movable unit 46 itself is used, the tracking and focusing coils 31 and 32 formed of the thin coil 33 of the coil unit 10 are in a state of reversal on the peripheral surface,
On the other hand, when the inner peripheral surface of the member surrounding the movable unit 46 is used, the coils 31 and 32 face each other on the peripheral surface.

[0038]

As is apparent from the above description, in the coil unit according to the first aspect, the space factor of the ribbon coil is increased and the magnetomotive force is improved although the weight of the entire coil unit is not so increased. Therefore, both a thin coil unit and high magnetic characteristics can be obtained. In addition, the connection work of the coil unit is facilitated.

In the coil unit according to the second aspect of the present invention, an appropriate connection position is ensured by placing the thin coil on the flexible wiring board, so that the conductive connection work becomes extremely easy and reliable connection is possible. . As a result, the connection operation can be automated, and disconnection due to poor connection, bending of the flexible wiring board, or the like can be prevented.

Further, in the coil unit according to the third aspect, when the thin coil is placed on the flexible wiring board, the two are firmly engaged with each other, so that the mountability on the bonding surface is improved and the flexible wiring board is mounted on the mounting surface. When the flexible wiring board is attached to the flexible wiring board, it is possible to prevent stress from being applied to the conductive connecting portion or the fixed portion between the ribbon coil and the flexible wiring board due to bending of the flexible wiring board. Accidents can be prevented.

The optical pickup device of claim 4 is
Since the magnetomotive force is improved and a small and not so heavy coil unit is mounted on the outer peripheral surface of the movable unit and driven,
It becomes an optical pickup device with extremely high sensitivity. Moreover,
By improving the mounting properties, automation of production or improvement of mass production efficiency can be aimed at, and the production cost can be reduced. In addition, the thinning of the coil unit and the high magnetic properties make the optical pickup device smaller and more sensitive. Can be achieved.

In addition, in the optical pickup device according to the fifth aspect, since one of the pair of ribbon coils can be used as a focus drive coil and the other can be used as a tracking drive coil, both of the drive coils have high sensitivity. It can be.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of an embodiment of a coil unit according to the present invention, wherein (A) is a plan view and (B) is a sectional view.

FIGS. 2A and 2B are views showing a ribbon coil used in the coil unit according to the present invention and an attached state thereof, wherein FIG. 2A is an enlarged cross-sectional view taken along an arrow A showing the structure of the ribbon coil, and FIG. It is an expanded sectional view showing the mounting structure of the coil in the coil unit.

FIG. 3 is an explanatory view showing a method of bonding a flexible wiring board and a drive coil in the embodiment of FIG. 1;

4A and 4B are explanatory views showing a method of conductively connecting a drive coil and a power supply wiring layer in the embodiment of FIG. 1, wherein FIG. 4A shows a state in which solder is attached to a connection surface portion, and FIG. The state of flowing down to the connection pad is shown.

FIG. 5 is a schematic sectional view showing a schematic structure of an embodiment of an optical pickup device equipped with a coil unit according to the present invention.

FIG. 6 is a side view showing a shape of a coil unit adapted to the optical pickup device shown in FIG.

FIG. 7 is a graph showing the sensitivities of the optical pickup device equipped with the coil unit according to the present invention and a conventional optical pickup device, wherein the X axis represents the sensitivity of the focus driving coil;
The Y axis indicates the sensitivity of the tracking drive coil.

FIG. 8 shows the relationship between the thickness t2 of the electric insulator layer of the coil and the withstand voltage.
It is a graph which shows a relationship.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible wiring board 10 Coil unit 12 Power supply wiring layer 31 Focus drive coil (thin coil) 32 Tracking drive coil (thin coil) 36 Metal foil (conductive film) 37 Electrical insulator layer 38 Electrical insulator layer Resin electrical insulation layer constituting the electrical insulation layer 39 Resin adhesive layer constituting the electrical insulation layer

Claims (5)

(57) [Claims] 1. A flexible wiring board having a power supply wiring layer, a conductive thin film and an electric insulating layer of 2 to 6 μm are alternately wound and fixed with one end face abutting on the substrate surface. A coil having a slice thickness of 0.18 to 0.30 mm, wherein the power supply wiring layer is conductively connected to a winding end of the ribbon coil. 2. A connecting exposed portion of the power supply wiring layer is disposed immediately below or inside an inner peripheral surface of the ribbon coil and directly below or outside an outer peripheral surface of the ribbon coil. The coil unit according to claim 1, wherein the inner and outer peripheral surfaces of the coil are conductively connected with a conductive connecting material. 3. The coil unit according to claim 1, wherein the end surface of the ribbon coil is formed in a shape that matches the mounting surface shape of the flexible wiring board. 4. The thin strip of the coil unit, wherein the flexible wiring board of the coil unit according to claim 1 is mounted on a peripheral surface formed around an axis of a movable unit. An optical pickup device, wherein the coil is a driving coil for the movable unit. 5. The optical pickup device according to claim 4, wherein the coil unit is a coil unit to which at least a pair of opposed or opposed thin ribbon coils are fixed on the peripheral surface.