JPH01201833A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To heighten tracking control sensitivity and to reduce power consumption by providing a focusing coil and plural rectangular tracking coils, and generating driving force in the same direction on an effective coil part and a return coil part. CONSTITUTION:When a current flows through the focusing coil 17 wound around a bobbin 13, the driving force in the focusing direction of an objective lens 11 is generated on the bobbin 13 combining with the magnetic flux of a magnet 19. And arm parts 15 and 16 which support the bobbin 13 on a yoke 14 are displaced in an up-and-down direction by bending and rocking. Next, when the current flows to the plural rectangular tracking coils 18, the driving force moving the bobbin 13 in a tracking direction is generated by synthesizing the magnetic flux of a magnetic intermediate part 19c and the return magnetic flux of antimagnetization parts 19a and 19b. Then, the arm parts 15 and 16 are moved horizontally. In such a way, the tracking control sensitivity can be heightened, and also, the power consumption is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an objective lens that focuses a light beam emitted from a light source onto a signal recording surface of an optical disk, for example, in a focusing direction, a tracking direction, or any one of these directions. The present invention relates to an objective lens driving device that changes drive to one side.

[Summary of the invention]

The present invention is an objective lens driving device for driving and displacing an objective lens in a focusing direction and a tracking direction, and the present invention includes a bobbin to which the objective lens is attached, a focusing coil for driving the objective lens in a direction parallel to its optical axis, and a bobbin that is attached to a bobbin to which the objective lens is attached. A tracking coil that drives the objective lens in a direction perpendicular to its optical axis is attached, and a magnet that faces the focus coil and tracking coil with a predetermined gap to form a magnetic field is attached to the tracking coil. By magnetizing the objective lens so that the direction of the driving force generated by the magnetic flux from each side parallel to the optical axis is in the same direction, the sensitivity of the objective lens in the tracking direction is improved, reducing power consumption. Improved vibration resistance,
This makes it possible to improve reliability by reducing leakage magnetic flux.

[Conventional technology]

Conventionally, an optical pickup has been used as a means for reading information signals recorded on the optical disk or writing predetermined information signals on the optical disk by irradiating a light beam onto the signal recording surface of an optical disk that is mounted on a disk rotation drive device and rotated. equipment is used. This optical pickup device has an objective lens that focuses a light beam emitted from a semiconductor laser as a light source onto the signal recording surface of an optical disk, and uses a magnetic driving force to move the objective lens in a focusing direction, a tracking direction, or one of these directions. An objective lens drive device is provided which causes the light beam to focus on the signal recording surface of the optical disk and accurately scan the recording track by driving and displacing the objective lens.

As shown in Fig. 7, an objective lens drive device commonly used in conventional optical pickup devices includes a drive coil for supporting an objective lens (1), a drive coil for focus control, and a drive coil for controlling a plurality of rectangular trackings. The bobbin (4) with the drive coil (3) attached is placed between the magnets (7), which are fixed to the yokes (6), +6) placed oppositely on the base (5), and the base ( 5) The installation installed on the top is supported in a cantilevered manner by a metal support rod (9) with spring properties that is suspended horizontally in a cantilevered manner in parallel to the top and bottom of the front left and right parts of the board (8). It is known that it is composed of In this configuration, the bobbin (4) is either the focus control drive coil (2) or the tracking control drive coil (
3) is moved by the elastic displacement of the support rod (9), and the objective lens (1) supported by the bobbin (4) is moved in the focusing direction and the tracking direction.

[Problem to be solved by the invention]

By the way, in the conventional objective lens drive device configured as described above, the tracking control drive coil (3) is wound into a rectangular shape, and the left and right sides are not perpendicular to the focus control drive coil (2). direction, i.e. objective lens (
The return portion of this tracking control drive coil (3) is attached to the magnet (7), (7) in order to prevent forces from being generated in the opposite direction during movement in the tracking direction. ), the output from the drive force generating section of the tracking control drive coil (3) is small, resulting in low sensitivity.

To solve this problem, driving in the focusing direction and driving in the tracking direction can be performed separately, but if the magnetic field is not shared in this re-driving, the cost will be high, so as shown in Fig. 7 above. As shown in the figure, the configuration is such that the magnetic field is shared. However, with this configuration, in order to increase the output of the driving force in the tracking direction, the supplied power must be increased, which is disadvantageous in that it is expensive to use.

Therefore, the present invention solves the problems of the conventional ones as described above, has a simple structure, has good sensitivity to the power supplied for control, and can drive the objective lens with good response. An object of the present invention is to provide an objective lens driving device.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides at least a bobbin to which an objective lens is attached, a focusing coil attached to the bobbin and driving the objective lens in a direction parallel to the optical axis of the objective lens, and a focusing coil that drives the objective lens in a direction parallel to the optical axis of the objective lens. A tracking coil that drives the objective lens in a direction perpendicular to its optical axis is made up of a plurality of substantially rectangular coils that are symmetrically attached to the bobbin, and the tracking coil faces the focus coil and the tracking coil with a predetermined gap. It is equipped with a magnet that is magnetized so that the direction of the driving force generated by the magnetic flux from each side parallel to the optical axis of a plurality of approximately rectangular coils is in the same direction, and the focus coil and tracking The coils are arranged in a common gap, and the objective lens is driven in a direction parallel to the optical axis and in a direction perpendicular to the optical axis.

[Effect]

In this way, the focus coil attached to the bobbin to which the objective lens is attached and a plurality of substantially rectangular tracking coils are opposed to each other with a predetermined gap to form a magnetic field. By magnetizing so that the direction of the driving force generated by the magnetic flux from each side parallel to the axis is the same, leakage magnetic flux is reduced and the return coil part also works effectively in tracking drive of the objective lens. Sensitivity is improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to an optical pink amplifier device.

The objective lens drive device of this example, that is, the optical pick amplifier device includes an objective lens (11) and an optical pickup unit 1-(
A bobbin (13) as a movable body that integrally incorporates a bobbin (12)
) as a frame to the yoke (14) as a support member. @2 arm member (15).

(16), it is supported so as to be movable in a direction parallel to the optical axis of the objective lens (11), that is, a focusing direction, and in a direction orthogonal to the optical axis, that is, a tracking direction.

The bobbin (13) in this configuration is made of heat-resistant and highly rigid synthetic resin, such as AB or S resin, in the shape of a box, and the objective lens (11) is fitted onto the top surface of the bobbin (13) with the optical axis in the vertical direction. Inside, there is a semiconductor laser as a light source, a beam shifter and reflection mirror that guides the light beam from the semiconductor laser to the objective lens, and a photodetector that detects the return beam reflected from the optical disk through a beam splitter. An optical pickup unit (12) consisting of a detector and the like is built-in. This bobbin (
13), there is a focus control drive coil (hereinafter referred to as focus coil') (
17) is wound, and a tracking control drive coil (hereinafter referred to as a tracking coil) is wound on this coil (17) in a substantially rectangular shape located on both sides of the front and rear surfaces.
(18) is attached by bonding or the like.

Further, the yoke (14) is formed as a quadrilateral frame, and the yoke portions (14a) on the front and rear sides.

Inner yoke (14&1) inside each of (14b).

(14bt) is provided with a protruding cross-sectional shape.

A focus coil (
Magnets (19), (19) facing the tracking coil (17) and tracking coil (18) are fixed, and these magnets (19), (19) and the yoke (1
4) constitutes a magnetic circuit.

Both ends of the magnets (19), (19) have lengths corresponding to the tracking coils (1B), (1B) located on both sides of the front and rear surfaces of the bobbin (13),
Tracking coils (18), (1
An end portion (19a) corresponding to the outer side portion of 8),
(19b) has the magnetization direction reversed from that of intermediate e (19c). Below, this magnet (19), (19)
both ends (19a).

(19ti) is called a reverse magnetization section.

The arm members (15) and 16) that support the bobbin (13) with respect to the yoke (14) have a pair of front and rear hinge parts and upper and lower parallel links, and are made of elastic synthetic resin. As mentioned above, the objective lens (1
1) is moved in the focus direction by the swinging action of the parallel link, and by bending and swinging at the front and rear hinges, the object lens swings laterally in the form of a parallel link together with the bobbin (13) and yoke (14). (11) is moved in the tracking direction.

In addition, on both sides of the bobbin (12), a band-shaped flexible printed wiring board (
20) is connected as a power supply lead line, and the rear side yoke part (14b) of the yoke (14) is twisted 90 degrees.
) is fixed to the upper edge side and guided outward.

In the above configuration, magnets (19), (1
As shown in Fig. 2, the magnetic flux from the middle part (19c) reaches the inner yoke (14&ri, (14bt) side) through the focus coil (17),
9c), there are reversely magnetized parts (19a), (
The magnetic flux returns to the 19b) side.

In this way, magnets (19), (19)
The magnetic flux from the center (19c) is the focus coil (17) and the tracking coil (1B).

The return magnetic flux passes through the inner part of (18), that is, the inside of the effective coil part, and returns to the oppositely magnetized parts (19a) and (19b). I will pass.

The objective lens drive device as an optical pickup device of this example configured as described above has a focus coil (17) wound around a bobbin (13) through a flexible printed wiring board & (20) as a power supply lead line. When the drive current is supplied, the magnet (19) of the magnetic circuit (
Together with the magnetic flux from 19), the driving force that moves the bobbin (13) upward or downward, that is, in a direction (focus direction) parallel to the optical axis of the objective lens (11) attached to the bobbin (13), is generated. Occur.

Arm members (15) and (16) that support this bobbin (13) with respect to the cork (14) are bent upward or downward in parallel at the upper and lower parallel links and swing, thereby supporting the bobbin (13). is displaced upward or downward in parallel, and the objective lens (11) is accordingly moved in the focus direction.

Furthermore, when a driving current is supplied to the tracking coil (18) through the flexible printed wiring board (20), the magnetic flux from the magnets (19), (19), that is, the magnetic flux from the intermediate part (19c) and the reversely magnetized part (19a)
, (19b) causes the tracking coil (1B), (1B) to generate a driving force in the same direction as the effective coil part in the return coil part, so that the bobbin (13) is moved laterally, that is, in the objective direction. Direction perpendicular to the optical axis of the lens (11) (tracking direction)
It will be moved to.

Then, the arm members (15) and (16) that support the bobbin (13) with respect to the yoke (14) are bent leftward or rightward at the front and rear hinge portions, so that the bobbin (13) is Displaced laterally, ie to the left or to the right. This lateral displacement of the bobbin (13) is caused by a parallel link operation as a whole by the arm members (15) and (16) that actuate the bobbin (13) and yoke (14) in the left-right direction. This is carried out in a horizontal state, and the objective lens (11) is accordingly moved in the tracking direction.

In this example, the tracking coil (1B)
, (1B) generates effective driving force also in the return coil section, so the sensitivity of the objective lens (11) in the tracking direction can be increased, making it possible to reduce power consumption and improve vibration resistance. In addition, the magnetic flux of the magnets (19) and (19) is reversely magnetized on both sides (
19a) and (1'9b), leakage magnetic flux in the vertical direction is reduced and reliability is improved.

In the above configuration, reverse magnetization portions (19a) are provided on both sides.

(19b) with magnet (19), (19
) can be realized by making the magnetic path run in opposite directions at both ends of the magnet using a magnetizing yoke. Also, the magnets (19) and (19) are magnetized in the middle part (19c).
) and both sides (19a) and (19b), and further three magnets, that is, both sides magnet (19a) which is reversely magnetized with respect to the middle magnet (19c). , (19b
) can also be formed by bonding them together.

And the magnet (19) formed in this way.

(19) is a double-sided magnetized part (19) compared to the middle part (19c).
a).

If the magnetic force of (19b) is too strong, use the focus coil (
17) Since the return magnetic flux passing through the center increases and the sensitivity in the focus direction decreases, it is necessary to optimize the balance between the magnetic forces of the middle part (19c) and both oppositely magnetized parts (19a) and (19b). be.

Next, another embodiment of the present invention will be described with reference to FIG. 3. This embodiment is an objective lens driving device configured such that the trasoking operation of the objective lens (11) is performed by rotational movement.

In this example, only the objective lens (11) is the movable body (2).
3), and drive control coils are attached to both left and right sides of this movable body (23), and both movement control coils are connected to a focus coil (1) wound into a rectangular tube shape.
7a) and (17b) are formed by fixing tracking coils (18) formed in a rectangular shape on both sides of the outer surfaces thereof.

The movable body (23) is rotatably and vertically movably attached to the base board (24) by one support arm (25) having a horizontal hinge portion and vertical parallel links, and is capable of controlling the drive on both sides. Coil focus coil (17
a), (17b) is an inner yoke (24a1) formed in a raised shape on the base substrate (24).

(24bt) and tracking coil (18bt).
) is the outer yoke (2462), (24b
A magnet (29) fixed to the inner surface of the
(29) are opposed to each other with a required gap. These magnets (29), (29) also have both end portions (29a), (29b) in the middle portion (
29c) to form a reverse magnetization section, which corresponds to the return coil section of the tracking coil (18).

In this example configured in this way, the magnet (29
), (29), that is, the intermediate part (29c
) and the reverse magnetization part (29a), (29
The return magnetic flux to the tracking coil (1
8) generates a driving force in the same direction as the effective coil part in the return coil part, so that the movable body (23) can be rotated with good sensitivity around the hinge part of the support arm (25) as a fulcrum, that is, as a center of rotation. The objective lens (11) is movable in a direction perpendicular to the optical axis (tracking direction).

FIG. 4 shows still another embodiment of the present invention, in which the objective lens is driven by an open magnetic field, and the objective lens (11
) attached bobbin (33) near orcus coil (1
7) is wound on the coil (17), and tracking coils (18) having the same rectangular shape are fixed on both sides of the front and rear surfaces.

The bobbin (33) is mounted vertically on the base crystal & (34) parallel to the optical axis of the objective lens (11) by support bars (35) and (36) having spring properties on the plate (34a). The inner surfaces of the yokes (34b) and (34c) are supported so as to be swingable in the direction of the yoke and in the orthogonal direction, and the front and rear surfaces including the tracking coil (18) are formed in an upright manner on the base substrate (34). (39) and (39) are opposed to each other with a required gap.

These magnets (39) and (39) also have both ends (3
9a).

(39b) is reversely magnetized with the intermediate portion (39c) to form a reversely magnetized portion, which corresponds to the return coil portion of the tracking coil (ratio).

In this example configured in this way, the magnet) (3
9), the magnetic flux from (39), that is, the middle part (39c
) to the reversely magnetized parts (39a) and (39b) passes through the outer return coil part of the tracking coil (18), and this return coil part also generates a driving force in the same direction as the effective coil part. child
.

Therefore, the motion sensitivity of the bobbin (33) in the tracking direction is increased, and the objective lens (11) is reliably moved in the direction perpendicular to the optical axis, that is, in the tracking direction.

In addition, in the case of this example, as shown in Figure 5, the magnet
By creating magnetic fields in opposite directions at both ends of (39) and (39), the external magnetic field in the vertical direction (within the thin wire) can be reduced, that is, leakage magnetic flux can be reduced, and reliability is improved.

In addition, in the embodiment shown in FIGS. 3 and 4, the magnets (29) and (39) do not have opposite magnetic parts at both ends thereof, and are similar to the conventional example as shown in FIG. 6. It is formed by unidirectional magnetization with a length corresponding to the effective coil part of both side tracking coils (18), and one side outer surface side yoke (2
482) + (24b2) and (34b),
(34c) is formed in such a shape that both ends thereof protrude toward the inner surfaces of the magnets (29) and (39).
The return magnetic flux of 9) is attracted and the tracking coil (
As in the above-described embodiment, a driving force is generated in the same direction as the effective coil part in the return coil part of the tracking coil (18), and the same driving force as described above is generated in the return coil part of the tracking coil (18). Effects can be obtained.

Although the present invention has been described in detail above, the present invention is not limited to these embodiments, and can be modified in various ways without departing from the spirit of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, drive in the same direction is generated on each side parallel to the optical axis of the objective lens, that is, on the effective coil portion and the return coil portion, in the tracking control drive coil having a substantially rectangular shape. By making the magnet celadon, it is possible to increase the tracking control sensitivity of the bobbin to which the objective lens is attached, reducing power consumption and improving vibration resistance. It is possible to provide an objective lens driving device that has various advantages, such as improved reliability due to reduced leakage magnetic flux, and no increase in cost because the number of component parts does not increase.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an example of an objective lens driving device according to the present invention, FIG. 2 is an explanatory diagram of the operation of the device shown in FIG. 1, FIG. 3 is a perspective view of another example, and FIG. 4 is a further example of another example. 5 is an explanatory diagram of the operation of the apparatus shown in FIG. 4, FIG. 6 is an explanatory diagram of the operation of a modified example, and FIG. 7 is a perspective view of the conventional example. In the figure, (11) is the objective lens, (13), (23)
. (33) is a bobbin (movable body), (14a), (1
4b). (24&2), (24b2), (34b)
, (34c) is the yoke, (17) is the focus coil, (18) is the tracking coil, (19),
(29), (39) are magnets, (19)
a), (19b), (29a),
(29b). (39a) and (39b) are reversely magnetized parts.

Claims (1)

[Claims] A bobbin to which at least an objective lens is attached; a focus coil attached to the bobbin and driving the objective lens in a direction parallel to its optical axis; a tracking coil that is made up of a plurality of substantially rectangular coils attached to the bobbin and drives the objective lens in a direction perpendicular to its optical axis; magnets arranged to face each other and magnetized so that the directions of driving forces generated by magnetic flux from each side parallel to the optical axis of the plurality of substantially rectangular coils are in the same direction; An objective lens driving device, wherein the focus coil and the tracking coil are arranged in a common magnetic gap, and the objective lens is driven in a direction parallel to the optical axis and in a direction perpendicular to the optical axis.