JPH08203104A - Multilayer printed coil for driving lens - Google Patents

Abstract

PURPOSE: To reduce the thickness and weight of printed coils for driving lens by laminating focusing coils and tracking coils and connecting the respective layers by through-holes, thereby forming these printed coils. CONSTITUTION: The printed coils are formed by laminating 20-21-22-23 in this order, alternately arranging the driving coils in a focusing direction and the driving coils in a tracking direction and electrically connecting the printed coils to each other by plating of the through-holes 24 to 30. The current in one of current paths flows from the terminal 28A of the printed coil 20 via the through-hole 29 to the coil electrode 34 of the printed coil 21, the through- hole 25, the coil electrode 36 of the printed coil 22, the coil electrode 35, the through-hole 24, the coil electrode 33 of the printed coil 21, the through-hole 30 and the terminal 28B of the printed coil 20. The current of the other current path flows from the terminal 28C of the printed coil 20 to the coil electrode 31, the through-hole 26, the coil electrode 37 of the printed coil 23, the coil electrode 38, the through-hole 26, the coil electrode 32 of the printed coil 20 and the terminal 28D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving print coil for driving a lens for optically storing or reading an information signal in a disc player or the like.

[0002]

2. Description of the Related Art An objective lens is driven in the lens optical axis direction (focusing direction) in order to focus a reading beam from a disc in which information is optically stored on a disc surface, and the reading beam is made to follow an information track. In addition, there is known a pickup device which is driven in a tracking direction which is a direction perpendicular to the lens optical axis direction (for example, Japanese Patent Publication No. 61-18261). In this pickup device, in order to have a structure of small size, light weight, and low power consumption,
A focusing coil and a tracking coil are formed on the coil bobbin, and the lenses are driven in the two-dimensional direction by utilizing mutually orthogonal forces acting on the coil.

[0003]

However, the Japanese Patent Publication No. 61-
When a focusing coil and a tracking coil in which coil portions intersecting each other in a substantially orthogonal state are formed in a common magnetic flux as in Japanese Patent No. 18261, a distance from a magnet and its thrust are generated by the focusing coil and the tracking coil. Since the direction of the effective conductor line segment is different, a force that bends or distorts the coil unit occurs due to the difference in the magnitude, direction, and position of the force point of the generated thrust. For this reason, harmful vibrations are generated in the coil, and resonance particularly occurs in the high frequency region, and it cannot be used in applications requiring high response speed.

In view of the above points, it is an object of the present invention to provide a lens driving print coil which suppresses harmful vibrations caused by the focusing coil and the tracking coil.

[0005]

In order to solve the above-mentioned problems, a lens-driving print coil according to a first aspect of the present invention comprises a drive coil for driving a lens in the lens optical axis direction and a direction perpendicular to the optical axis direction. The driving coil to be driven is formed by a plurality of laminated print coils, and the plurality of print coils are reinforced by through holes penetrating between the plurality of print coils.

In the lens driving print coil according to a second aspect of the present invention, the through hole is reinforced by a plated through hole. Claim 3
The lens driving print coil described above is characterized in that the through hole is provided on a line that coincides with a driving direction of each of the driving coils.

[0007]

Since the print coils are reinforced by the through holes, harmful vibration can be suppressed even if the print coils are made extremely lightweight.

[0008]

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, which is a lens driving coil in which a focusing coil and a tracking coil are integrally formed by stacking print coils. In the figure, 20 to 23 are print coils having a coil formed on the surface, 28A to 28D are terminals for external connection, 24 to 30 are through holes, and 31 to 38 are coil poles. Although not shown, each coil pole is formed with a thin spiral coil, and the printed coil can be manufactured by a known technique.

The print coil is 20-21-22-23
The driving coils in the focusing direction and the driving coils in the tracking direction are alternately arranged. The print coils are electrically connected to each other by plating the through holes 24 to 30. Therefore, the current flowing through the coil flows as follows.

First, one of the current paths is the print coil 2
Coil pole 34 of print coil 21, through hole 25, coil pole 36 of print coil 22, coil pole 35, through hole 24, coil pole 33 of print coil 21, and through hole 30 from terminal 28A of 0 through through hole 29. , To the terminal 28B of the print coil 20.

Another current path is the print coil 20.
From the terminal 28C to the coil pole 31, the through hole 26, the coil pole 37 of the print coil 23, the coil pole 38, the through hole 26, the coil pole 32 of the print coil 20, and the terminal 28D. Next, an example in which such a laminated printed coil is arranged is shown in FIG. As shown in FIG. 4, the stacked print coils are provided between the magnet 11, the yoke 12 and the yoke 13. Note that in FIG. 4, the positional relationship between the focusing coil and the tracking coil is shown in FIG.
Different from the laminated printed coil of No. 1, one drive coil is composed of 14A and 14B, and the other drive coil is composed of 15A.
It is composed of A and 15B, and shows the case where the drive coils are not alternately arranged.

The magnet 11 is monopolarly magnetized on the plane, and the drive coil 14 is formed by connecting two print coils 14A and 14B through a through hole 14C.
A vertical thrust is generated by passing a current in the 4D direction, and the drive coil 15 is formed by connecting two print coils 15A and 15B with a through hole of 15C.
A lateral thrust is generated by passing an electric current in the 5D direction. Therefore, the lens mounted integrally with the coil can be driven in the focusing direction as well as in the tracking direction, which is the direction perpendicular thereto. Note that FIG.
It is a sectional view of (A).

Next, as shown in FIG.
An example in which the poles are magnetized will be described.
As shown in FIG. 5, the magnet 40 is magnetized to have two poles with respect to the plane. In such a case, as shown in FIG. 2, the print coils 41, 42, 43 and 44 are laminated in this order and connected by through hole plating to obtain a focusing coil and a tracking coil.

In FIG. 2, 41 to 44 are print coils, 45A to D are terminals, 46 to 63 are through holes, 5
1 to 59 are coil poles. Print coil 4 here
The current to 2, 43 is from the terminal 45A to the through hole 46.
Via the coil pole 51 of the print coil 42, the through hole 60, the coil pole 55 of the print coil 43, the coil pole 57, the through hole 62, the coil pole 53 of the print coil 42, the coil pole 54, the through hole 63, and the print coil. It flows through the coil pole 58 of 43, the coil pole 56, the through hole 61, the coil pole 52 of the print coil 42, and the through hole 47 to the terminal 45B of the print coil 41.

Further, the current to the print coils 41 and 44 is applied from the terminal 45C of the print coil 41 to the coil pole 5.
0, through hole 49, coil pole 59 of print coil 44, through hole 48, terminal 4 of print coil 41
It flows to 5D. The through holes 46 to 49 are provided so as to penetrate the four print coils.
0 to 63 are provided so as to penetrate only the print coils 42 and 43.

FIG. 3 shows an example of through hole connection for a laminated structure of a print coil. Although the arrangement and structure of through-hole connection differ depending on the coil formation pattern, it is preferable to form the through-holes in as many layers as possible, and preferably to penetrate all layers. The size of the through hole provided for the purpose of the present invention must be 0.1 mm or more and 2.0 mm or less, preferably 1.2 mm or less as the diameter of the hole. That is,
If it is too small, the effect of preventing vibration does not occur, and if it is too large, the through hole itself is distorted, so that the effect is also small.

On the other hand, the land is effective if it has a hole diameter or more, but it needs to be 2.0 mm or less, preferably 1.2 mm or less. This is because the eddy current that is generated becomes larger when the range is larger than the above range, and when the actuator operates, a force that hinders the movement is generated and a loss occurs.
Further, it is preferable from the viewpoint of vibration prevention that the through-hole plating is installed at the center of the area where the drive coil is installed, especially on a line symmetrical with respect to the tracking / focusing direction, excluding the terminal portion. That is, it is particularly effective to provide the through hole in the center of the installation area of the tracking coil and the focusing coil of the print coil.

Although the through-hole plating of the present application is shown to be used also for electrical connection, it may be used for mechanical purposes only. In addition, the laminated structure of the print coil that forms the tracking coil (T) and the focusing coil (F) has, for example, four layers, T-TF-F, and T-TF-F.
Although it may be formed in the order of stacking -F-T-F, T
It is preferable that the print coils are symmetrically stacked, such as -FFT or FTTF.

Furthermore, solder through holes may be used for the connection of the through holes, but it is preferable to use the plated through holes in terms of symmetry. FIG. 6A shows the frequency characteristic of the lens driving device using the print coil of FIG. 1, and FIG. 6B shows the frequency characteristic of the lens driving device using the print coil not connected by through hole plating. Indicates. As shown in FIG. 6 (B), 500H
Although there is a peak near z and harmful vibration is generated, in the embodiment of the present invention, it is gentle from 20 Hz to 10 kHz, and it can be seen that no harmful vibration is generated.

[0020]

As described above, the lens driving print coil of the present invention can be made extremely thin and lightweight by stacking the focusing coil and the tracking coil and connecting the respective layers by through holes, and at the same time, through holes can be formed. It is possible to prevent vibrations due to thrusts of different layers, that is, focusing and tracking directions.

It is more preferable to connect the through holes with the plated through holes because the plated through holes have symmetry. Further, since the through holes are provided on the lines that coincide with the drive directions of the respective drive coils, vibration can be particularly reduced.

[Brief description of drawings]

FIG. 1 is a pattern diagram of four print coils that constitute a drive print coil according to an embodiment of the present invention.

FIG. 2 is a pattern diagram of four print coils constituting a print coil unit according to another embodiment of the present invention.

FIG. 3 is a laminated sectional view of another embodiment of the present invention.

FIG. 4 is a layout view and a cross-sectional view of a driving print coil according to an embodiment of the present invention.

5 is a diagram showing a form of a magnet used in combination with the driving print coil of FIG.

6A is a frequency characteristic of a lens driving device using the print coil of FIG. 1, and FIG. 6B is a frequency characteristic of a lens driving device using a multilayer laminated print coil that does not use through-hole plating.

[Explanation of symbols]

11 magnets 12, 13 yokes 14A, 14B, 15A, 15B drive coils 14C, 15C, 24-30, 46-63 through holes 20-23, 41-44 print coils 28A-D, 45A-D terminals 31-38, 51 ~ 59 coil poles

Claims (3)

[Claims] 1. A drive coil for driving a lens in a lens optical axis direction and a drive coil for driving a lens in a direction perpendicular to the optical axis direction are formed by a plurality of laminated print coils, and the plurality of print coils are provided. The lens driving coil is reinforced by a through hole penetrating between the plurality of print coils. 2. The lens driving coil according to claim 1, wherein the through hole is reinforced by a plated through hole. 3. The lens driving coil according to claim 1, wherein the through hole is provided on a line that matches a driving direction of each of the driving coils.