JPH09293254A - Optical pickup and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the reading of information till the innermost periphery of tracks of an optical disk by preliminarily prolonging a center line for objective lens supporting in a direction separating away from a motor for driving at the stationary state of a biaxial actuator for an objective lens. SOLUTION: When a virtual center line VL is drawn from the center of the objective lens 14 of a biaxial actuator 10 toward a sliding shaft 13 being in a supporting side, this virtual center line VL is prolonged in a direction separating away gradually from a spindle motor 26. Then, this optical pickup is made so tint when the objective lens 14 is moved to the left end of a tracking stroke, the objective lens 14 can converge a light beam on the innermost periphery of an optical disk D. Consequently, the optical disk D made to cope with a high density recording is rotatingly driven by the spindle motor 26 having a large diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording and / or reproducing a disc-shaped recording medium such as a CD (compact disc) or a magneto-optical disc, and an optical disc apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, an optical disk device for recording and / or reproducing an optical disk has an optical pickup for focusing a light beam on a signal recording surface of the optical disk. Furthermore, this optical pickup is equipped with a recording track on the signal recording surface of the optical disc.
An objective lens actuator for slightly moving the focusing objective lens by a slight distance is provided. This objective lens actuator is also called a biaxial actuator because it moves the objective lens in the tracking direction so as to follow the recording track and also in the focusing direction which is the optical axis direction orthogonal to the tracking direction. ing.

FIG. 15 is a plan view showing a schematic structure of an optical pickup provided with such a biaxial actuator. In the figure, the optical pickup 4 includes an optical system including an optical element attached to a slide base 4a. The optical pickup 4 is arranged on one surface side of the optical disc D, usually on the lower surface side. Then, with respect to the optical disc D, a drive motor 4e which is a spindle motor for rotationally driving the optical disc D is disposed on the same one side where the optical pickup 4 is disposed.

The slide base 4 has a long bearing portion 4b extending in the axial direction at one end, and a guide shaft 4d is mounted on the bearing portion 4b so that the biaxial actuator 1 is attached. , And is sent in the same direction as the tracking direction Trk in FIG.

An integrated type light emitting / receiving element 4c is mounted on one side of the slide base 4a. This light emitting / receiving element 4c,
A light source, a separation element that separates the light emitted from the light source from the return light reflected by the recording surface of the optical disc, and a photodetector for receiving the return light and detecting a signal are provided. There is. The light beam emitted from the light source of the light emitting / receiving element 4c passes through the objective lens 5 of the biaxial actuator 1 mounted on the slide base 4a, and the driving motor 4e.
The signal storage surface of the optical disc D that is driven to rotate is irradiated. The return light reflected by the signal recording surface is guided to the photodetector (not shown) of the light emitting / receiving element 4c via the objective lens 5.

Here, the biaxial actuator 1 supports the objective lens 5 held on one side of the lens holder 2 formed of a mold resin and the like, and rotatably supports the lens holder 2, and at the same time, on the paper surface. The lens holder 2 includes a slide shaft 3 slidably supported in a vertical direction, and electromagnetic driving means 6 provided in pairs on the left and right side portions of the lens holder 2.

The electromagnetic drive means 6 is integrally formed and has a yoke 7 having metal plates facing each other, and a magnet 7a provided inside one of the metal plates facing each other.
And a focusing coil 8 formed by winding a winding wire in parallel with a plane formed by the paper surface of FIG. 15 and arranged in a magnetic field formed between the magnet 7a and the other metal plate. The tracking coil 9 is formed by winding a winding wire in a direction orthogonal to the winding direction of the focusing coil 8.

In such a biaxial actuator 1, the lens holder 2 slides the objective lens 5 on the sliding axis based on the action of the focusing coil 8 and the magnetic field formed by the magnet 7a and the yoke 7. 3 is moved in the focusing Fcs direction along the extending direction.
Further, based on the action of the tracking coil 9 and the magnetic field formed by the magnet 7 a and the yoke 7, the electromagnetic driving means 6 moves the objective lens 5 of the lens holder 2 around the sliding axis 3 in the tracking Trk direction. To move. As a result, the light from the light emitting / receiving element 4c forms a spot of an accurate size on the signal recording surface of the optical disc D via the objective lens 5, and this spot can follow the recording track accurately. .

[0009]

However, in such an optical pickup 4, the slide base 4 has the structure shown in FIG.
As shown in (4), it is necessary to prevent interference with the spindle motor 4e when the optical disc D is fed to the innermost circumference along the guide shaft 4d. Then, as shown in FIG. 15, when the optical pickup 4 is moved to the innermost side of the optical disc D, the biaxial actuator 1 is in a stationary state and is positioned at the innermost track position of the optical disc D. There is a need to. Here, the distance L1 from the center of the optical disc D to the innermost track position of the track is constant according to the standard.

On the other hand, in recent years, the information recording density of the optical disc D is becoming higher, and accordingly, the rotation driving motor 4e of the optical disc D also needs to rotate the optical disc D at a high speed.

However, if the rotation driving motor 4e can be rotated at a higher speed, the outer diameter of the motor 4e becomes larger, and the optical pickup 4 having the structure as shown in FIG.
The biaxial actuator 1 cannot move the objective lens 5 to the position of the innermost track of the optical disc D. That is, when the objective lens 5 is moved to the inner peripheral side of the optical disc D up to the distance L1 in FIG. 15, there is a problem that the slide base 4a interferes with the drive motor 4e.

The present invention has been made to solve the above problems. Even if a drive motor compatible with high rotation is adopted, it does not interfere with the outer diameter of the drive motor and is the innermost track of the optical disk. It is an object of the present invention to provide an optical pickup capable of reading information up to the circumference and an optical disc device using the optical pickup.

[0013]

According to the present invention, the above object is to provide an optical system for irradiating an optical disk with light through an objective lens and detecting return light from a signal recording surface of the optical disk by a photodetector. In the pickup, the tracking drive coil and the focusing drive coil are arranged in the magnetic field of the magnet, and the objective lens is driven in the tracking direction and the focusing direction with respect to the optical disk based on the current flowing in each coil and the magnetic flux penetrating each coil. The biaxial actuator is configured to move from the objective lens, which is the movable side, to the support side that supports the objective lens in a static state in which the drive coil is not energized. The center line of the side away from the drive motor for rotating the optical disk The optically pickups extending is achieved.

According to the above construction, the biaxial actuator for finely moving the objective lens of the optical pickup supports the objective lens from the movable side of the objective lens in a static state in which the drive coil is not energized. An imaginary center line extending toward the supporting side extends away from the drive motor for rotationally driving the optical disk.
Therefore, the objective lens is located closer to the inner circumference side of the optical disc than the conventional one when the biaxial actuator is in the static state. Then, the objective lens moves by the tracking operation centering on this stationary position. Therefore, since the objective lens is located on the inner circumference side of the optical disc, the optical pickup can be located away from the center of the optical disc, and the outer diameter of the drive motor is increased accordingly. Also, the outer diameters of the optical pickup and the drive motor do not interfere with each other.

The static state of the biaxial actuator is
The state in which the drive current is not applied to the tracking coil.

[0016]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 is a block diagram showing a configuration example of an optical disk device to which the optical pickup of this embodiment is applied. The optical disk device 25 includes a spindle motor 26 as a driving unit that rotationally drives the optical disk D. The spindle motor 26 is drive-controlled by an optical disk drive controller 27, as will be described later, and particularly drives the optical disk D to rotate at a high speed. The optical pickup 28 irradiates the signal recording surface of the rotating optical disc D with light so as to record a signal and detects the return light reflected by this signal recording surface. A reproduction signal based on the returning light is output to the device 31. The optical disc D includes various optical discs such as compact discs having recording pits and magneto-optical discs.

The recording signal demodulated by the signal demodulator 31 is error-corrected by an error correction circuit 33 and sent to an external computer or the like via an interface 34. As a result, the external computer etc.
The signal recorded in can be received as a reproduction signal. To the optical pickup 28, for example, a head access control unit 30 for moving to a predetermined recording track on the optical disc D by a seek operation or the like is connected. Further, at the moved predetermined position, the objective lens is moved with respect to the objective lens actuator (biaxial actuator) that holds the objective lens of the optical pickup 28, which will be described later, with respect to the optical disc D.
A servo circuit 29 for moving in the approaching and separating directions and the tracking direction (radial direction of the optical disc D) is connected.

FIG. 2 is a plan view showing a preferred embodiment of the above-mentioned optical pickup, FIG. 3 is a sectional view taken along the line DD of FIG. 2, and FIGS. 4 and 5 are respectively taken along the line BB. And C-
FIG. 6 is an enlarged sectional view taken along the line C-A of FIG. In FIG. 2, the optical pickup 28 includes a slide base 50.
The optical system is composed of an optical element attached to. The optical pickup 28 is arranged on one surface side of the optical disk D, usually on the lower surface side. A drive motor 26, which is a spindle motor for rotating the optical disc D, is disposed on the same side of the optical disc D as the optical pickup 28 is disposed on. The spindle motor 26 as the drive motor is a large-sized spindle motor having a larger diameter than the conventional spindle motor shown by the dotted line M in FIG.

The optical pickup 28 includes the slide base 50, the biaxial actuator 10 attached to the slide base 50 and moved in the radial direction of the optical disc D, and the light emitting / receiving element 16 attached to the slide base 50. It has an optical system consisting of the optical element of.

As shown in FIGS. 3 and 6, the slide base 50 has a long bearing portion 5 extending in the axial direction at one end thereof.
3 and a pair of oil-impregnated bearings 51 and 52 provided in the bearing portion 53. This pair of oil-impregnated bearings 5
By attaching a guide shaft (not shown) to the shafts 1, 52, the two-axis actuator 10 is attached, and
Is sent in the same direction as the tracking direction Trk of.

As shown in FIG. 4, an integrated light receiving / emitting element 16 is mounted on one side of the slide base 50. The light emitting / receiving element 16 includes a light source, a separating element for separating the light emitted from the light source from the return light reflected by the recording surface of the optical disc, and a signal receiving element for receiving the return light and detecting a signal. It is equipped with a photodetector and the like. The light from the light emitting / receiving element 16 is guided to the internal space of the slide base 50, is reflected by the raising mirror 17 provided with the reflection surface inclined by 45 degrees with respect to the optical axis, and is reflected by the objective lens 14. Incident. In addition, the return light from the optical disc is
It is reflected by the rising mirror 17 via the objective lens 14 and guided to the light emitting / receiving element 16.

As shown in FIG. 3, the slide base 50 is provided with a sliding shaft 13 extending vertically. As shown in FIGS. 2 and 3, the sliding shaft 13 slidably supports the vicinity of the center of the lens holder 12 of the biaxial actuator 10. The sliding shaft 13 is designed to reduce the frictional force between the sliding shaft 13 and the lens holder 12 as much as possible, and for example, its surface is coated with a lubricant. The biaxial actuator 10 has the lens holder as a movable part formed by resin molding or the like. The lens holder 12 has an objective lens 14 mounted on one end side around the shaft hole of the sliding shaft 13 formed on the lens holder 12, and a balance with the objective lens 14 on the other end side 15. It has a balancer which is a weight for taking.

In particular, in this embodiment, the biaxial actuator 10 is arranged as follows. When a virtual center line VL is drawn from the center of the objective lens 14 of the biaxial actuator 10 toward the sliding shaft 13 on the supporting side,
The imaginary center line VL extends in a direction gradually away from the spindle motor 26 in FIG. In other words, the biaxial actuator 10 is arranged obliquely with respect to the direction orthogonal to the direction in which the bearing portion 53 of the slide base 50 extends.

By arranging the biaxial actuator 10 so that the virtual center line VL is as shown in FIG. 2, the objective lens 14 is closer to the left end in the figure of the slide base 50 as compared with the conventional one. Can be located (see FIG. 15). Then, when the objective lens 14 moves to the left end of the tracking stroke by the tracking movement shown by the arrow in FIG.
Enable to focus the light beam on the innermost circumference of the optical disc D. That is, the objective lens 14 is moved to the position L1 in FIG. In this case, the end of the slide base 50 is
It is located outside the conventional position in the radial direction of the optical disc D.

Therefore, as much as the slide base 50 can be arranged outside, the spindle motor 26
Can have a diameter larger than that of a conventional spindle motor (shown by a chain line M). As a result, the large-diameter spindle motor 26 can rotate the optical disc D compatible with high-density recording at high speed.

Next, the structure of the biaxial actuator 10 will be described in more detail. In the plan view of FIG. 7 and the side view of FIG. 8, only the lens holder 12 is illustrated in detail with the objective lens positioned on the right side. In FIG. 2 or 7, the lens holder 12 has a constricted shape on both sides, and a pair of electromagnetic drive means 40 are provided in this portion, respectively. This electromagnetic drive means 40
2 have the same structure on the left and right of FIG. 2, and the detailed structure is shown in FIG. That is, a pair of metal plates 41a and 41b facing each other, which serve as yokes, stand upright from the slide base 50 side. The metal plates 41a and 41b are integrated at the lower end, and the upper end is made of a metal bridge plate 41.
It is blocked by c. A magnet (permanent magnet) 42 is fixed inside the outer metal plate 41b. The magnet 42 is magnetized so that one side thereof has a single pole, S or N pole, that is, the front and back surfaces have different polarities of N pole and S pole, respectively.

As a result, the magnetic flux emitted from the magnet 42 enters the other metal plate 41a and forms a parallel magnetic field in this region. In this case, the bridge plate 41c may be omitted, but the presence of the bridge plate 41c allows the closed magnetic circuit to be accurately formed, which is preferable in terms of forming a magnetic field. In this parallel magnetic field, the focusing coil 4
5 and tracking coils 43, 43 are arranged.

The focusing coil 45 is formed by winding a coil in a rectangular shape in FIG. 2, and an effective conductor portion of the coil corresponding to one long side of the coil is arranged in the parallel magnetic field. Tracking coils 43, 4
As shown in FIG. 8 in which the side surface of the lens holder 12 is enlarged, the two reference numerals 3 are provided side by side by bonding or the like so as to overlap the focusing coil 45. The winding direction of the winding of each tracking coil 43, 43 is a ring shape along the direction orthogonal to the plane including the winding direction of the focusing coil 45.

As a result, due to the action of the magnetic flux of the parallel magnetic field and the current flowing through the focusing coil 45, the lens holder 12 and the objective lens 14 attached thereto are finely moved in the focusing direction Fcs shown in FIG. Further, due to the action of the magnetic flux of the parallel magnetic field and the current flowing through the tracking coils 43, 43, the lens holder 12 and the objective lens 14 mounted on the lens holder 12 move in the tracking direction T of FIG.
It is slightly moved to rk. These focusing coils 45,
Each terminal of the tracking coils 43, 43 is shown in FIG.
As shown in FIG. 3, the flexible substrate 46 is connected to the fixed side. As a result, electric power required for driving each coil is supplied from the fixed side.

Further, preferably, by the following constitution, the middle point of the lens holder of the biaxial actuator can be held. As shown in FIG. 2, FIG. 5, FIG. 7, etc., in the parallel magnetic field, the focusing coil 45
A magnetic body 44, which is a midpoint position holding means for holding the midpoint position of the lens holder 12, is fixed to the inside of the by means of adhesion or the like. The magnetic body 44 may be made of any material that can be attracted to the magnet, and is made of, for example, iron, nickel, cobalt, or an alloy thereof. This magnetic body 4
Reference numeral 4 is for always holding the lens holder 12 at the center point of the moving range of tracking and focusing without energizing both coils for tracking and focusing. Therefore,
In the case of a biaxial actuator having a magnet on the movable side, it is provided on the fixed side. In this embodiment, as shown in FIG. 8, the magnetic body 44 is formed in a cross shape.
As shown in FIG. 7, there are two cross-shaped magnetic bodies 44, one for each electromagnetic drive means 40. The magnetic body 44 will be described in detail below.

The operation principle of the midpoint holding by the magnetic body 44 will be described. FIG. 9 shows a case where the midpoint is held in the lateral direction of the drawing. The magnet is magnetized to have a single pole on one side. The magnetic body has a laterally elongated shape, is aligned with the lateral length of the magnet, and is arranged in a parallel magnetic field. In FIG. 9 (a), the magnetic body is held at the midpoint in the lateral direction, and the magnetic fluxes from the magnet to the yoke are parallel to each other at this time, and the magnetic field strength is uniform and symmetrical with respect to the center of the magnetic body. ing. In contrast, FIG.
As shown in (b), when the magnetic body is moved to the left in the figure, the magnetic flux is pulled by the magnetic body and moves to the left.
The force that the magnetic flux tries to return so as to become parallel magnetic flux forming a parallel magnetic field becomes a restoring force for holding the midpoint of the magnetic body. When the magnetic body moves to the right, the restoring force works in the opposite direction by the same principle.

On the other hand, FIG. 10 is a state in which FIG. 9 is viewed from the side and explains the reason why the restoring force does not work in the left and right directions of the drawing. When the lateral length of the magnetic body is smaller than the length of the magnet, the magnetic flux is uniform left and right and the restoring force does not work regardless of the position of the magnetic body in the lateral direction. From the above, as shown in FIG.
When holding the midpoint in the horizontal direction, the horizontal length of the magnetic body must match the horizontal length of the magnet, and the vertical length is the stroke required for movement. Make it smaller. When holding the midpoint in the vertical direction,
As shown in FIG. 1 (b), the length of the magnetic body in the vertical direction needs to match the length of the magnet in the vertical direction, and the horizontal length is reduced by the stroke required for movement.

In this case, the size of the magnet corresponds to the intersection of the direction in which the magnetic flux extends and the effective spread of the parallel magnetic field, and the size of the magnetic field in the vertical and horizontal directions. Therefore, depending on how the magnets are arranged, even if the magnet as a component is large, if the peripheral edge of this magnet is magnetically sealed when it is attached to the equipment, the size of the magnetic body is Must be smaller than the magnet.

Further, when the lens holder 12 is held at the neutral point (midpoint), the resonance frequency f ₀ is generated in the focusing direction and the tracking direction with respect to the holding force F. In a biaxial actuator, this resonance frequency f ₀
Since it is necessary to determine a certain value, the size of the magnetic material is also limited in this respect. For example, the resonance frequency in the focus direction is expressed by the following equation.

[Equation 1] If “m” is the mass of the moving part and “k” is a kind of spring constant,

[Equation 2] It is.

In this case, the mass of the movable part such as the lens holder has a constant value m, and F is almost determined by the volume of the magnetic material.
The volume of the magnetic body can be determined by the thickness and width of the magnetic body (the restriction on the length is as described above), but the thickness should be as thin as possible in consideration of the efficiency of the magnetic circuit. In this respect, the thickness of the magnetic body is about 0.1 to 0.3 considering the convenience of the assembling process. Therefore, k will be proportional to F,
By determining F, the resonance frequency f ₀ can be set to a certain value. The width of the magnetic material is determined on the condition of the value of F. This point has the same relationship as the resonance frequency f ₀ in the tracking direction.

Thus, the magnetic body 44 of this embodiment is constructed as shown in FIGS. That is, the magnetic body 44 includes a first portion 44a having the same dimension as the height L1 of the magnet 42 in the height direction, and a second portion 44b having the same dimension as the width L2 of the magnet 42 in the width direction. Consists of. The first portion 44a and the second portion 44b are formed integrally with each other by intersecting each other so that they intersect each other at the center. As a result, in the magnetic body 44, the magnet 4
It is possible to hold the midpoint in both the height and width directions with respect to 2.

FIG. 14 shows the electromagnetic drive means 40 on the left side of FIG.
It is the partial expanded sectional view which looked at from the lower side. As shown in the drawing, by arranging the magnetic body 44 inside the focusing coil 45 in the parallel magnetic field, the lens holder 12 that is a movable portion is moved in two directions of the tracking direction Trk and the focusing direction Fcs in FIG. The midpoint can be held at the same time. In this case, the lens holder 12
Since it is supported by magnetic force and holds the midpoint,
Since the lens holder 12 is not pressed against the sliding shaft 13, a large frictional force does not occur between the sliding shaft 13 and the shaft hole of the lens holder 12.

Therefore, when the lens holder 12 is moved for tracking or focusing, it is possible to perform smooth servo without causing difficulty in movement.

As described above, according to the optical pickup of this embodiment, even if a large-diameter spindle motor capable of rotating an optical disk at high speed is used, it does not interfere with the outer diameter of the motor. An optical pickup suitable for high-density recording can be obtained. Further, if the center point of the lens holder is held, the lens holder can be held at the center point on the servo that slightly moves the objective lens in the static state.

The present invention is not limited to the above embodiment. In particular, the biaxial actuator is not limited to the shaft sliding type described above, and is a type that supports a lens holder, which is a movable part, with an elastic support member (a leaf spring that supports one end fixed to a fixed part). This midpoint holding structure can also be applied to a biaxial actuator of a type in which the movable part holding the objective lens is supported by a supporting member having a plurality of hinge parts corresponding to the tracking direction and the focusing direction. This midpoint holding structure can be applied.

[0042]

As described above, according to the present invention, even if a driving motor compatible with high rotation is adopted, the innermost track of the optical disk can be reached without interfering with the outer diameter of the driving motor. It is possible to provide an optical pickup capable of reading information and an optical disc device using the optical pickup.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical disc device to which the present invention is applied.

FIG. 2 is a plan view showing an optical pickup, a biaxial actuator, and a slide base used in the optical disk device of FIG.

3 is a cross-sectional view of the biaxial actuator and the slide base of FIG. 1 taken along the line D-D.

FIG. 4 is an enlarged cross-sectional view of the biaxial actuator and the slide base of FIG. 1 taken along the line BB.

5 is an enlarged sectional view of the biaxial actuator and the slide base of FIG. 1 taken along the line C-C.

6 is a cross-sectional view taken along the line AA of the biaxial actuator and the slide base of FIG.

7 is a plan view showing a lens holder of the biaxial actuator of FIG. 1. FIG.

8 is a side view showing a lens holder of the biaxial actuator shown in FIG. 1. FIG.

9A and 9B are explanatory views for explaining the action of the magnetic body of the biaxial actuator of FIG.

10 is an explanatory diagram for explaining the action of a magnetic body of the biaxial actuator of FIG.

FIG. 11 is an explanatory diagram for explaining the action of the magnetic body of the biaxial actuator of FIG. 1.

12 is a schematic perspective view showing a configuration of a magnet of the biaxial actuator of FIG.

13 is a schematic perspective view showing a configuration of a magnetic body of the biaxial actuator of FIG.

14 is a cross-sectional view showing a main part of the midpoint holding structure of the biaxial actuator of FIG.

FIG. 15 is a plan view showing an example of a conventional optical pickup.

[Explanation of symbols]

10 ... Biaxial actuator, 12 ... Lens holder (movable part), 13 ... Sliding shaft, 14 ... Objective lens, 16 ... Light emitting / receiving element, 40 ... Electromagnetic driving means, 41a, 41b ... Yoke, 42 ... Magnet, 43 ... Tracking coil, 44 ... Magnetic body, 45 ... Focusing coil, 25 ... Optical disk device

Claims (4)

[Claims] 1. An optical pickup for irradiating light onto an optical disc through an objective lens and detecting return light from a signal recording surface of the optical disc by a photodetector, wherein a tracking drive coil and focusing are performed in a magnetic field of a magnet. A driving coil is arranged, and a biaxial actuator that drives the objective lens in the tracking direction and the focusing direction with respect to the optical disc based on the current flowing in each coil and the magnetic flux passing through each coil is provided. In a static state in which the drive coil is not energized, a virtual center line from the movable objective lens to the support side supporting the objective lens is a drive for rotating the optical disc. Optical pick, characterized in that it extends in a direction away from the motor for Up. 2. The tracking coil, the focusing coil, or a member for holding these coils,
The optical pickup according to claim 1, wherein a magnetic body having a size that at least partially matches the height and width of the facing surface of the magnet is disposed at a position facing the magnet. 3. The magnetic field is a parallel magnetic field, the magnetic body is arranged at a position intersecting with the magnetic flux of the parallel magnetic field, and at the intersecting surface, the magnetic body has a height and a width in which the magnetic field spreads. The optical pickup according to claim 2, wherein the sizes are substantially the same in at least a part. 4. A drive unit for driving the optical disc to rotate, an optical pickup for irradiating the optical disc with light through an objective lens and detecting return light from a signal recording surface of the optical disc with a photodetector. A signal processing circuit that generates a reproduction signal based on a detection signal from the photodetector; and a servo circuit that moves the objective lens of the optical pickup in the tracking and focusing directions based on the detection signal from the photodetector, The optical pickup includes a tracking drive coil and a focusing drive coil in a magnetic field generated by a magnet, and tracks the objective lens with respect to the optical disc based on the current flowing in each coil and the magnetic flux penetrating each coil. Equipped with a biaxial actuator that drives in both direction and focusing direction The biaxial actuator is an imaginary straight line extending from the center of the objective lens on the movable side to the center of the fixed side supporting the objective lens in a static state in which the drive coils are not energized. The optical disc device extends in a direction away from a drive motor as the drive unit for rotationally driving the optical disc.