JPS60254426A - Objective lens driving device used for optical information reader - Google Patents

Abstract

PURPOSE:To completely eliminate the lead wire, etc., projected from a movable section and to simplify the constitution, by providing at least two pieces of bobbins closely to a coil for driving in the focus direction and winding coils for driving in the track direction around the bobbins. CONSTITUTION:A coil 26 for driving in the focus direction is wound around magnets 24a and 24b so as to cover the magnets 24a and 24b and a set of bobbins 25 and 25 is installed to positions respectively facing the magnets 24a and 24b at the outside. Then coils 27 and 27 for driving in the track direction are respectively wound around the bobbins 25 and 25. The magnets 24a and 24b are driven by an electric current made to flow through the coils 27 for driving in the track direction provided closely to the coil 26 for driving in the focus direction covering the magnets 24a and 24b. The electric current flowing through the sections of the coils 27 and 27 wound around the bobbins 25 and 25 nearer to the magnets 24a and 24b flows in the opposite direction to the electric current flowing through the section farther from the magnets 24a and 24b and their driving directions are also opposite to each other. When the thickness of the bobbins 25 and 25 is maintained at a prescribed value or more, the influence of the coils at the farther side can be eliminated.

Description

[Detailed Description of the Invention] (1) Purpose of the Invention] The first year of the invention! The present invention relates to an objective lens driving device used in a device that optically reads information digitally recorded on a disk-shaped recording medium.

In general, in order to record various input signals using a recording medium such as a compact disc (CD disc), it is necessary to convert them into bits, that is, digital signals of "0" and "1", and then write and read them. In this method, an optical pickup equipped with an objective lens is moved along the disk surface, and a laser beam is used for detection by optical means.

The reading device described above requires an optical system that can use an objective lens to focus light onto a spot of the same size as a small hole (bit) recorded on the disk, and has good spatial coherence. In addition to using laser light, focusing control and tracking control between the objective lens and the disk must be performed accurately. Therefore, the objective lens installed in the optical pickup must be of a two-dimensional drive type that can be moved and adjusted in both the focus direction, that is, the direction perpendicular to the disk surface, and the track direction, that is, the radial direction of the disk surface. is necessary.

As a conventional driving device for the above-mentioned two-dimensional drive type objective lens, a voice coil for driving in the focus direction,
A movable coil type drive device using a flat coil or the like for driving in the track direction is often used. For example, in the case of the conventional example shown in FIG. 7, the objective lens 1 is
It is fixed to the objective lens support member 2, and is fitted so that the objective lens support member 2 can move in the track direction T and the focus direction F by a guide shaft 3 passing through the center position. On the outer peripheral surface of the objective lens support member 2, there is provided a flat coil 4 for driving in the track direction as shown in FIG.
, 4 are arranged, and a focusing direction driving coil 5 is wound around the outside thereof, and a magnet 6 shown in FIG.
, is disposed within a magnetic gap 8 formed by the yokes 7a and 7b.

FIG. 10 is a plan view showing the arrangement of the above-described main components.

In the above configuration, when a current is applied to the focus direction drive coil 5, the objective lens support member 2 can be moved in the focus direction F based on magnetic interaction.

On the other hand, the track direction drive coil 4 is configured using four pieces in the illustrated example, and the current flows in the same direction within the magnetic gap 8. The lens support member 2 can be moved in the track direction T. 1 shown in Figure 7
0 is a fixed substrate, and the other end of the lead wire 11 soldered to the ends 9a and 9b of the substrate 9 fixed to the upper surface of the objective lens support member 2 is soldered to the fixed substrate 10 and led out to the outside. As a result, power is supplied when each coil is energized.

Problems to be Solved by the Invention However, such conventional objective lens driving devices have the drawback that the shape of each coil is complicated and the number of man-hours during manufacturing increases. That is! - In the illustrated example, four rack direction drive coils 4 are required, and each coil must be electrically connected, making the assembly operation cumbersome. In addition, since a large number of lead wires P for supplying electricity to each coil are drawn out, care must be taken at all times to dispose of these lead wires, and there are other drawbacks such as the risk of adversely affecting the vibration characteristics of the drive unit. have.

The present invention eliminates the various drawbacks that occur due to the structure of the objective lens drive device used in the conventional optical information reading device as described above, simplifies the structure, reduces the manufacturing process, and eliminates the need for external protrusions such as lead wires. The objective is to provide an objective lens driving device that is easy to handle and has good vibration characteristics by eliminating the parts.

(2) Means for Solving the Problems Between Structures of the Invention In order to achieve the objects of the present invention, a guide shaft is provided that passes through a support member to which an objective lens is fixed, and a guide shaft is provided along which the objective lens is fixed. The objective lens is formed so that it moves in the focus direction of the disc-shaped recording medium and also moves in the 1-rack direction of the disc-shaped recording medium, and the periphery of the magnet fixed to the opposing portion of the objective lens support member is A coil for driving the objective lens in the focus direction is wound so as to cover the objective lens, at least two bobbins are disposed adjacent to the coil for driving the focus direction, and a coil for driving the objective lens in the 1-rack direction is wound around the bobbin. The main objective is to obtain an objective lens drive device for use in an optical information reading device, which is characterized by having a coil wound thereon.

Example Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a perspective view showing the entire first embodiment of the present invention. In the figure, reference numeral 21 denotes an objective lens, which is fixed to an objective lens support member 22. As shown in FIG. This objective lens support member 22
The inner peripheral part of the guide cylinder part 22a (FIG. 2) formed integrally with the guide shaft 2 that protrudes through the objective lens support member 22
3 and is slidably and rotatably fitted. Therefore, the objective lens support member 22 is formed to slide in the focus direction F of a disc-shaped recording medium (not shown) and rotate in the 1-rack direction T.

A pair of magnets 24a and 24b are fixed to opposing parts of the objective lens support member 22, and are adapted to slide and rotate integrally with the objective lens support member 22. The pair of magnets 24a and 24b are arranged so that their opposing surfaces have the same polarity (S) as shown in FIG. 4, and their outer sides are formed into a cylindrical shape.

A coil 26 for driving in the focus direction is wound so as to cover the magnets 24a and 24b, and a pair of bobbins 25 and 25 are arranged close to each other on opposite sides of the coil 26. coil 27.27
Wrap it around. This track direction drive coil 27°27
are wound around a bobbin 25.25 so that current flows in the same direction on the sides close to the magnets 24a, 24b, and the bobbins 25.25 are set so that the distances from the guide shaft 23 are equal to each other, Moreover, it is fixed to the main body 32 side. By forming the outside of the magnets 24a, 24b into a cylindrical shape, even if the magnets 24a, 24b rotate, the distance between the adjacent track direction drive coils 27 is always constant. A balance weight 28 is fixed to the lower side of the objective lens support member 22 so that the center of gravity of the rotating portion of the objective lens support member 22 coincides with the guide shaft 23.

Further, as shown in FIGS. 2 and 3, a viscoelastic member 29 such as silicone rubber is inserted between the rod 30 protruding from the objective lens support member 22 and the rod 31 protruding from the main body 32. The movable part is prevented from falling from the guide shaft 23 even when the lens is turned upside down, and the objective lens 21 can be set at a substantially neutral position.

The operation of the objective lens driving device according to the present invention described above is as follows. First, when the focus direction driving coil 26 is energized, the magnets 24a and 24b, which are movable parts, move in the focus direction F together with the objective lens support member 22 due to magnetic interaction with the magnets 24a and 24b, thereby driving the objective lens 21. For example, when the focus current shown by IF in FIGS. 4 and 5 is applied, the magnets 24a, 24
b moves in the direction of arrow F. On the other hand, when the track direction drive coil 27 is energized, and the current IT shown in FIG. 4 flows, the left magnet 24a moves to the other side of the paper.
The right magnet 24b moves toward the front of the page. Therefore, the objective lens support member 22 rotates in the right direction about the guide shaft 23. Note that the square symbol shown in FIGS. 5 and 6 indicates the direction of current flowing perpendicularly to the paper surface and on the opposite side, and the square symbol 1 indicates the direction of current flowing perpendicularly to the paper surface and on the near side. The direction in which the magnets 24a and 24b move is determined by the direction of the current.

” As is clear from the operation description in section 2, the magnet 24a.

The magnets 24a and 24b are driven by a current flowing through a track direction drive coil 27 provided adjacent to a focus direction drive coil 26 that covers the magnets 24b.
Among the track-direction driving coils wound around the bobbin 25, 25, current flows in opposite directions in the coils located close to the magnets 24a and 24b and the coils located far away, and the driving directions are also reversed. However, by keeping the thickness of the bobbin 25°25 above a predetermined value, the influence of the coil on the far side can be eliminated.

In this embodiment, it is desirable to reduce the weight of the objective lens support member 22 and the magnets 24a, 24b that constitute the movable part, and the weight of the objective lens support member 22 and the magnets 24a and 24b are preferably made of lightweight plastic.
, 24b is preferably a plastic magnet.

(3) One Momme U of the Invention By using the present invention described in detail above, the following operational effects can be obtained. That is.

With the guide shaft 23 passing through the objective lens supporting member as the center of rotation, a magnet fixed to the objective lens interacts with a coil wound around the magnet and a coil fixed to the main body. Since the objective lens support member and the objective lens move in the focus direction and the track direction,
There are no lead wires or the like protruding from the movable part, and the configuration is simplified.

Therefore, the number of manufacturing steps is reduced, making it easy to manufacture and reducing costs. As described above, by eliminating the need to draw out the lead wire from the movable part, it becomes easier to use and handle, and it is possible to bring about various effects such as improved vibration characteristics.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first embodiment of the device of the present invention, FIG. 2 is a plan view, FIG. 3 is a side view, and FIG. 4 is a sectional view taken along line IV-IV in FIG. 5 and 6 are enlarged views showing the working portion, and FIG. 7 is a perspective view showing an example of a conventional device.
FIG. 8 is a cutaway perspective view of the main part, FIG. 9 is a sectional view of the main part, and FIG. 10 is a plan view of the main part. 21... Objective lens, 22... Objective lens support member, 23... Guide shaft, 24a, 24b... Magnet, 25... Bobbin, 26... Focus direction drive coil, 27...・1
- Rack direction drive coil, 28... Balance weight, 29... Viscoelastic member, 32... Main body. Figure 1 Figure 2 Figure 3 Figure 4 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] (1) In an objective lens drive device installed in an optical information reading device that optically detects information recorded on a rotating disc-shaped recording medium, a guide for penetrating a support member to which the objective lens is fixed is provided. The objective lens is formed to move in the focus direction of the disc-shaped recording medium and rotate in the track direction of the disc-shaped recording medium along the guide shaft, and the objective lens support member A coil for driving the focus direction of the objective lens is wound so as to cover the periphery of a magnet fixed to opposing parts of the objective lens, and at least two bobbins are disposed close to the coil for driving the focus direction. An objective lens driving device for use in an optical information reading device, characterized in that a track direction driving coil is wound around the bobbin.