JPH0378119A - Tracking controller - Google Patents

Abstract

PURPOSE:To control an actuator with high accuracy by cancelling stress corresponding to the displacement of a leaf spring by using a generating means which outputs a DC bias voltage based on a current position signal. CONSTITUTION:A track address representing the latest current position is stored in a track address generation circuit 55, and it is supplied to a driving CPU 51, a search servo circuit 56, and a DC bias signal generation circuit 57. A DC bias signal conforming to the DC bias voltage which cancels the stress corresponding to the moving amount from a stable point is generated based on the current position signal at the DC bias signal generation circuit 57, and is supplied to an adder circuit 58, then, it is supplied to a tracking servo actua tor driving circuit 59. Therefore, a tracking servo operation and a search opera tion can be performed without receiving the influence of the stress of the stress of the leaf spring. Thereby, the control of the actuator can be performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tracking control device that controls a tracking servo actuator incorporated in an optical recording/reproducing device used in an optical disk device.

(Prior Art) In recent years, optical disk devices such as magneto-optical disk devices have been used for recording computer data, document files, and the like.

The magneto-optical disk cartridge used in this magneto-optical disk device is a magneto-optical disk for recording/playback that can be freely erased and rewritten, and is made of resin for ease of handling and to make it removable from the recording/playback device. It is housed in a case.

FIG. 6 is an explanatory diagram of recording and reproducing operations of an example of a small magneto-optical disk device incorporating a conventional tracking and feed control device.

As shown in the figure, a conventional small magneto-optical disk device 61
It is composed of a small magneto-optical disk 2, an electromagnet 5, a base 64, an optical recording/reproducing device 66, a feed device 78, a tracking/feed control device 80, and the like.

This conventional small magneto-optical disk 2 has a substrate 2a, which is a disc made of transparent resin such as polycarbonate, on one surface.
Fe for recording and reproducing information using magneto-optic effect
, Co, Tb, Gd, etc. magneto-optical film (MO film) 2b
A protective film 2C made of ultraviolet curing resin or the like is further formed on the protective film 2C, and a hub made of a metal plate (not shown) for driving the disk 2 is fixed to the center. It is housed in a resin case (not shown) and becomes a magneto-optical disk cartridge.

In the recording area 3 where information is recorded/reproduced on the magneto-optical film 2b of the disk 2, there are 1
．． A large number of recording tracks are formed at a pitch of 5 μl.

Each recording track is alternately formed with a data area where information is recorded/reproduced and a management area where management information is recorded in advance.

The disk 2 is moved at a CAV of 3.800 rpm by a spindle motor (not shown) fixed to the base 64.
The magneto-optical film 2. A bias magnetic field perpendicular to b is applied. Further, information is recorded and reproduced from the substrate 2a side onto the magneto-optical film 2b using the laser beam 15 from the optical recording and reproducing device 66.

This optical recording/reproducing device 66 includes a laser diode 7, a collimating lens 8, a beam splitter 9, a rising prism 10. objective lens 11, polarizing beam splitter 12,
Condenser lenses 13A and 13B.

It is composed of photodiodes 14A, 14B, etc.

The light emitted from the laser diode 7 is made into parallel light by the collimating lens 8, and then
The cross-sectional shape of the beam is shaped into a predetermined shape by a beam shaping prism (not shown), and the beam passes through the beam splitter 9 and enters the rising prism 10 . The laser beam 15 reflected by the raising prism 10 is formed by the objective lens 11 into a light spot 16 with a minute diameter on the surface of the magneto-optical film 2b on the recording track of the recording area 3 of the disk 2. is irradiated.

A light spot 16 irradiated onto the surface of this magneto-optical film 2b
has a light intensity suitable for recording when the device 66 is operating in the recording mode, and
When operating in the reproduction mode, the laser diode 7 is controlled by an output control device (not shown) so that it has a light intensity suitable for reproduction.

In this recording mode, the perpendicular magnetization direction of the magneto-optical film 2b on the recording track is reversed by the bias magnetic field of the electromagnet 5 only where the optical spot 16 hits, based on a digital signal corresponding to the recording data. This causes the digital signal to be recorded.

In the case of the reproduction mode, the direction of rotation of the polarization plane of the laser beam reflected on the surface of the magneto-optical film 2b changes depending on the perpendicular magnetization direction of the magneto-optical film 2b due to the magneto-optic effect. , the objective lens 11. The light is reflected by the beam splitter 9 via the rising prism 10, and is incident on the polarizing beam splitter 12 via a half-wave plate (not shown). The laser beam transmitted through this polarizing beam splitter 12 is focused by the condensing lens 13A, converted into an electric signal by the photodiode 14A, and output as a detection signal, and is reflected by this polarizing beam splitter 12. The collected laser light is focused by the condenser lens 13B, converted into an electric signal by the photodiode 14B, and output as a detection signal.

At this time, the magnitude of this rain detection signal changes in opposite directions depending on the rotation direction of the polarization plane due to the action of the polarizing beam splitter 12, so the reproduction of the digital signal is determined from the difference between the rain detection signals. It will be done.

Of the optical recording/reproducing device 66, a fixed unit 6-1 includes the laser diode 7, collimating lens 8, beam splitter 9, polarizing beam splitter 12, condensing lenses 13A, 13B, photodiodes 14A, 14B, etc. is fixed to the base 64, and includes a movable unit 66 including a focus and tracking servo actuator 70 in which the raising prism 10, objective lens 11, focus servo actuator 21, and tracking servo actuator 72 are integrated. -2 is the movable part 78 of the feed device 78;
It is installed in b. In this feed device 78, a movable portion 78b is fixed to the base 64, which is controlled by the control device 80, and moves the disk 2 along a guide rail (not shown) via a bearing 78c by the driving force of a near motor 78a. moving in the radial direction of the light spot 16
The recording track is searched by moving the disc 2 from the outer diameter to the inner diameter of the recording area 3, a so-called feeding operation. Note that this base 64 is configured to be held by the main chassis of the device 61 (not shown) via a vibration isolating mechanism (not shown).

Also, a so-called focus servo that automatically makes the focus of the optical spot 16 follow the surface of the magneto-optical film 2b due to surface deflection of the desk 2, etc., uses a focus servo signal based on the detection signal output. Based on this, the vertical position of the objective lens 11 is controlled by the focus servo actuator 21 mounted on the movable part 78b of the feed device 78.

In addition, the optical spot 16 is
The so-called tracking servo that automatically tracks the recording track on the recording track is based on a tracking servo signal based on the detection signal output from the management area, and the position of the objective lens 11 in the radial direction of the disk 2 is controlled by the movable part 78b. This is performed by controlling the tracking servo actuator 72 mounted on the vehicle. This actuator 72 is also controlled by the control device 80. The optical spot 16 on the disk 2 due to the tracking servo operation
Since the limit value of the radial movement range of the disc 2 is normally about several hundred μm, the radial positioning of the optical spot 16 on the disk 2 is performed using the tracking servo operation for precise positioning and the feed operation for coarse positioning. It has become.

Next, details of the tracking feed control device 80 will be explained with reference to FIG. 5.

FIG. 5 is a block diagram showing an example of a conventional tracking feed control device.

As shown in the figure, the conventional tracking/feed control device 80 includes a tracking servo circuit 53, a movement detection circuit 54, a track address generation circuit 55, a search servo circuit 56, a drive CPU 81, a tracking servo actuator drive circuit 89, and a feed device. Drive circuit 90
It is composed of etc.

A drive signal from the host CPU 17 provided in the device 61 instructing the search operation to move the optical spot 16 to the target track is sent to the drive CPU 81.
, a target track signal representing the destination track address is supplied from the drive CPU 81 to the search servo circuit 56. Further, as described above, the detection signal detected from the recording track of the disk 2 by the optical recording/reproducing device 66 is supplied to the tracking servo circuit 53, movement detection circuit 54, and track address generation circuit 55, respectively. .

This track address generation circuit 55 detects the track address recorded in the management area, and the address storage section provided in this circuit 55 always stores the track address representing the latest current position. The current position signal represented is supplied to the search servo circuit 56.

In this search servo circuit 56, based on the target track signal and the current position signal, the movable part unit 66-2 mounted on the movable part 78b of the feed device 78,
Therefore, a reference speed curve for moving the light spot 16 to the target track in the shortest time is calculated, and a search drive signal representing this speed information is supplied to the feed device drive circuit 90. Since the feed device drive circuit 90 supplies a drive voltage based on the search drive signal to the linear motor 78a of the feed device 78, the drive force of the linear motor 78a moves the movable portion 78b1 and the light spot 16 toward the target. Move towards the truck.

In the movement detection circuit 54, a movement speed is detected from the number of crossings of the recording track by the optical spot 16 per unit time, and a movement speed signal representing this movement speed is supplied to the search servo circuit 56. In this search servo circuit 56, the search drive signal is constantly corrected based on the moving speed signal, so that the light spot 16 reaches the target track in the shortest possible time, and the above-described search operation is performed.

The tracking servo signal representing the deviation of the optical spot 16 from the center of the recording track is generated in the tracking servo circuit 53, and based on this tracking servo signal, the tracking servo actuator drive circuit 89 drives the tracking servo actuator 72. A driving voltage is supplied, thereby performing the above-mentioned tracking servo operation. Further, the current position signal representing the current position after movement from the track address generation circuit 55 is supplied to the drive CPU 81, and in this drive CPU, arrival at the target track is confirmed by the current position signal. .

(Problems to be Solved by the Invention) The optical recording/reproducing device 66 is controlled by the conventional tracking/feed control device 80 having the above configuration.
As mentioned above, the two
Although it is a stage control method, it has problems such as slow access speed. In order to solve this problem, a one-stage control system has been proposed in which the tracking servo actuator 72 is removed and the feed device 78 performs both the tracking servo operation and the feed operation. This type of one-stage control system has problems such as poor controllability because the static and dynamic frictional resistance of the bearing 78c of the feed device 78 is large.

In order to solve this problem, the present applicant has proposed a type in which the feed device 78 is deleted and the tracking servo actuator is used to expand the movement range of the tracking servo actuator, thereby performing both the tracking servo operation and the feed operation. We have separately proposed a one-stage control system. The tracking servo actuator in this new one-stage control system eliminates the bearing 78c, and the movable unit 6
The movable part 6-2 is supported by a leaf spring that allows it to move only in the radial direction of the disc 2, and the mechanical stability point of this movable part is set at the radial center of the recording area 3 of the disc 2. At the same time, the optical spot 16 can be moved within the range from the outer diameter to the inner diameter of the recording area 3.

When controlling the tracking servo actuator of this new one-stage control method, when the movable part moves from a mechanically stable point toward the outer diameter or inner diameter of the recording area 3, it moves toward the mechanically stable point due to the restoring force of the leaf spring. Since the tracking feed control device 80 of the above-mentioned conventional example is subjected to stress,
The problem with this control is that highly accurate control cannot be achieved.

The present invention has been made in view of the above points, and an object of the present invention is to provide a tracking control device that enables highly accurate control of a tracking servo actuator using the above-mentioned new one-stage control method.

(Means for Solving the Problems) A tracking control device of the present invention includes a fixed part unit including at least a light emitting element that emits a laser beam and a light receiving element that obtains a detection signal from reflected light from an optical disk; A movable part comprising a rising prism that converts the optical axis of the light beam from the unit upward at a right angle, and an objective lens arranged on the optical axis of the light beam converted upward at a right angle and facing the recording area of the optical disk. The movable unit is incorporated into an optical recording and reproducing device consisting of a unit, and includes a leaf spring that allows the movable part of the movable unit to move only in the tracking direction, and the tracking servo operation and search operation are performed by moving the light spot produced by the objective lens. A tracking control device that controls a tracking servo actuator that performs the following, wherein a current position detection means that constantly detects the current position of the light spot outputs a current position signal, and a DC bias voltage is output based on the current position signal. The DC bias generating means is configured to cancel the stress corresponding to the displacement of the leaf spring.

(Example) The tracking control device of the present invention always detects the current position of the optical spot 16 in controlling the tracking servo actuator of the new one-stage control method described above, and uses a DC bias voltage according to this current position to By canceling the stress of the leaf spring, it is possible to control the actuator with high precision.

FIG. 2 is an explanatory diagram of recording and reproducing operations of an example of a small magneto-optical disk device incorporating a tracking control device according to an embodiment of the present invention.

As shown in the figure, a small magneto-optical disk device 1 incorporating a tracking control device 50 according to an embodiment of the present invention includes:
In addition to the control device 50, the tracking servo actuator and the feed device are different from the device 61 in the conventional example described above, so the same parts as in the conventional example described above are given the same reference numerals, and the explanation thereof will be given below. Omitted.

A focus and tracking servo actuator 20 controlled by a control device 50 according to an embodiment of the present invention incorporated in this device 1 includes the focus servo actuator 21 and the tracking servo actuator 3.
2 is integrally constructed, the feed device 78 in the conventional device 61 described above is omitted, and the tracking servo actuator 32 is used to perform both the tracking servo operation and the feed operation. be. Optical recording/reproducing device 6 in this device 1
The fixed parts of the focus servo actuator 21 and the tracking servo actuator 32 incorporated in the movable part unit 6-2 are fixed to the base 4, and the movement range of the tracking servo actuator 32 is as follows.
The optical spot 16 is configured to be movable in a range from the outer diameter to the inner diameter of the recording area 3 of the disc 2.

The configuration of the focus and tracking servo actuator 20 in FIG. 2 is schematically shown for explaining its operation, but the actual configuration is as shown in FIG. 3.

Fig. 3 shows an example of the actuator shown in Fig. 2; Fig. 3 (^) is a perspective view with the base removed; Fig. 3 (B) is a top view of Fig. 2 (A); Diagram (C)
is a side sectional view.

As shown in the figure, the focus and tracking servo actuator 20 according to one embodiment of the present invention has the following features as described above.
A focus servo actuator 21 and a tracking servo actuator 32 are integrally constructed.

This tracking servo actuator 32 is composed of a fixed part 33 and a movable part 38.
3 is composed of a rectangular plate-shaped magnet 34 magnetized in the thickness direction, an iron back yoke 35, a prismatic iron yoke 36, iron spacers 37A and 37B, and the like.

This yoke 36 is arranged so that the magnetized surface of the magnet 34 is
They are fixed at both ends via spacers 37A and 37B so that their surfaces are parallel with a predetermined gap, and a magnetic field is formed in this gap. The surface of this magnet 34 opposite to the surface facing the yoke 36 is fixed to the inner surface of the back yoke 35, and the upper end surface of this back yoke 35 is connected to the magnet 34 and the yoke 36.
It is fixed to the lower surface of the base 4 so that the longitudinal direction of the light beam 6 is parallel to the optical axis direction of the light beam from the fixed unit 6-1 of the optical recording/reproducing device 6.

This movable part 38 includes a rectangular cylindrical air-core coil 39, a resin movable part base 40, and two left and right leaf springs 41A and 41.
It is composed of B, etc.

This coil 39 is inserted into the yoke 36 with a predetermined gap maintained at the inner periphery of its hollow portion, and the surface of the coil side opposite to the coil side facing the magnetized surface of the magnet 340 is It is fixed to the center of the outer surface of the base portion 40a of the movable portion base 40, which is parallel to the magnetized surface. At the lower end of the inner surface of the base portion 40a of the movable portion base 40,
A rising prism holding section 40b is integrally formed at right angles to this base section 40a. A rising prism 10 is fixed to the tip of the rising prism holder 40b, corresponding to the optical axis of the light beam from the fixing unit 6-1, for converting the optical axis of the light beam upward at a right angle. Further, the leaf springs 4 are attached to the upper end portions of both ends of the inner surface of the base portion 40a.
One ends of the leaf springs 1A and 41B are fixed at right angles, and the other ends of the leaf springs 41A and 41B are fixed at right angles to both ends of the inner surface of a back yoke 24A, which will be described later. These two left and right leaf springs 41A and 41B are
With the focus servo actuator 21 (described later) arranged between them, the movable part 38 and the movable part 26 of the focus servo actuator 21 can be moved only in the optical axis direction of the light beam from the fixed part unit 6-1. The focus servo actuators 21 are arranged in parallel at intervals such that they do not come into contact with the focus servo actuator 21 during this movement.

The focus servo actuator 21 is connected to the fixed part 2
2 and a movable part 26, this movable part 26
is a coil 2 with two air cores in the shape of a rectangular tube with a rectangular cross section.
7A and 27B, a resin objective lens holder 28, a resin coil holder 29, and two upper and lower leaf springs 30A and 3.
It is composed of 0B, etc.

On the inner periphery of the cylindrical lens holder portion protruding from the center of the objective lens holder 28, a forelift raising prism 10 is provided.
The objective lens 11 is fixed, the center of which is located on the optical axis of the luminous flux converted upward at right angles. On the left and right sides of the rising prism 10 with respect to the optical axis direction of the light beam from the fixed part unit 6-1, coils are wound on the long side so that the winding direction of the coil side is parallel to the front axis direction. The coils 27A and 27B are arranged, and the upper end surfaces of the coils 27A and 27B are connected to the objective lens holder 2.
It is fixed to the left and right lower surfaces of the lens holder section 8. The lower end surfaces of the coils 27A and 27B are fixed to the left and right upper surfaces of the reinforcing coil holder 29. Rectangular holes having the same shape as the hollow portions of the coils 27A and 27B are formed in the portions of the objective lens holder 28 and coil holder 29 to which the coils 27A and 27B are fixed, respectively. This objective lens holder 28
One ends of the leaf springs 30A and 30B are each fixed at a right angle to the end face of the coil holder 29 on the base part 40a side, and the other ends of the leaf springs 30A and 30B are fixed to the inner surface of the base part 40a. are fixed at right angles to each other. These two upper and lower leaf springs 30A and 30B, with a magnet 23B and a back yoke 24B, which will be described later, arranged between them, move the movable part 26 to the light beam that is converted upward at right angles by the erecting prism 10. They are movable only in the axial direction, and are arranged in parallel at such intervals that they do not come into contact with the magnet 23B and back yoke 24B during this movement.

Further, the objective lens 11 is arranged to face the recording area 3 of the disk 2 (not shown) through a hole provided in the base 4. Further, when the movable part 38 of the tracking servo actuator 32 is at a mechanically stable point where the leaf springs 41A and 41B are not displaced, the light spot 16 is located at the radial center of the recording area 3, as described above. is set to be located.

The fixing part 22 includes prismatic magnets 23A and 23B magnetized in the thickness direction, back yokes 24A and 24B made of iron, rectangular plate-like iron yokes 25A and 25
It is composed of B, etc.

The yokes 25A and 25B are inserted into the center of the hollow portion of the coils 27A and 27B, respectively, while maintaining a predetermined gap from the inner periphery of each coil side.
Their upper end surfaces are fixed to the lower surface of the base 4, respectively. The magnets 23A and 23B have their magnetized surfaces aligned with the coils 27A and 27, respectively, so that a magnetic field is formed between them and the yokes 25A and 25B, respectively.
Each of B is arranged to face the surface of the coil side opposite to the rising prism 10 with a predetermined gap, and the surface opposite to the surface facing the coil side is respectively , are fixed to the inner surfaces of the back yokes 24A and 24B whose upper end surfaces are fixed to the lower surface of the base 4, respectively.

By sending the tracking servo signal to the coil 39 of the tracking servo actuator 32, the electromagnetic force received by the coil side of the coil 39 placed in the magnetic field in the gap between the magnet 34 and the yoke 36 causes This coil 39 moves in the longitudinal direction of the magnet 34 and the yoke 36, and therefore, the raising prism 10 moves on the optical axis of the light beam from the fixed unit 6-1, and the light spot 16 formed by the objective lens 11
The above-mentioned tracking servo operation is performed by moving in the radial direction of the disk 2. Also, the above-mentioned feed operation is also performed by this tracking servo actuator 3.
2 is similarly performed.

Further, by sending the focus servo signal to the coils 27A and 27B of the focus servo actuator 21, the coils 27A are arranged in the magnetic field in the air gap between the magnet 23A and the yoke 25A and between the magnet 23B and the yoke 25B. Due to the electromagnetic force received by the coil sides of coils 27A and 27B,
B moves in the vertical direction. Therefore, the objective lens 11 moves on the optical axis of the light beam converted upward at right angles by the raising prism 10, and the objective lens 11 directs the light spot 16 onto the disk 2. By moving in the plate thickness direction, the aforementioned focus servo operation is performed.

In order to damp harmful vibrations during the focus servo operation and the tracking servo operation, the leaf springs 30A, 30B, and 41A of the focus servo actuator 21 and the tracking servo actuator 32 are
Rubber damping materials 31A and 31B and 42A and 42B are bonded to and 41B, respectively.

Fig. 4 is a graph showing the relationship between the amount of movement of the movable part and the spring stress in the tracking servo actuator of Fig. 3, where the vertical axis is the spring stress applied to the movable part, the horizontal axis is the amount of movement of the movable part, and the zero point. represents the mechanical stability point.

As shown in the figure, the movable part 38 of the tracking servo actuator 32 is moved toward the mechanically stable point by the restoring force of the leaf springs 41A and 41B, which is proportional to the amount of movement from the mechanically stable point. subject to stress.

Next, details of the tracking TFI control device 50 will be explained with reference to FIG.

FIG. 1 is a block diagram showing an embodiment of a tracking control device of the present invention.

As shown in the figure, a tracking control device 50 according to an embodiment of the present invention includes a drive CPU 51, an electronic switch 52,
It is comprised of a tracking servo circuit 53, a movement detection circuit 54, a track address generation circuit 55, a search servo circuit 56, a DC bias signal generation circuit 57, an addition circuit 58, a tracking servo actuator drive circuit 59, and the like.

When a drive signal instructing the search operation to move the optical spot 16 to the target track is input from the host CPU 17 provided in the device 1 to the drive CPU 51, the drive signal is sent from the drive CPU 51 to the search servo circuit 56. Then, a target track signal representing the destination track address is supplied. Further, as described above, the detection signal detected from the recording track of the disk 2 by the optical recording/reproducing device 6 is supplied to the tracking servo circuit 53, movement detection circuit 54, and track address generation circuit 55, respectively.

This track address generation circuit 55 detects the track address recorded in the management area, and the address storage section provided in this circuit 55 always stores the track address representing the latest current position. The current position signal represented is supplied to the drive CPU 51, search servo circuit 56, and DC bias signal generation circuit 57, respectively.

In this search servo circuit 56, from the target track signal and the current position signal, the movable unit 6-2
A reference speed curve for moving the movable part of the , and hence the light spot 16, to the target track in the shortest time is calculated, and the search drive signal, which is this speed information, is applied to the two input terminals of the electronic switch 52. (lower input terminal in FIG. 1).

Further, the aforementioned tracking servo signal from the tracking servo circuit 53 is supplied to the other input terminal (the upper input terminal in FIG. 1) of this electronic switch 52.

During the search operation, the switching terminal of the electronic switch 52 is connected to the lower input terminal in response to a signal from the drive CPU 51, so that the search drive signal is supplied to the addition circuit 58.

On the other hand, in the DC bias signal generation circuit 57, based on the current position signal, a DC bias voltage corresponding to the DC bias voltage that cancels the spring stress according to the amount of movement from the mechanical stability point described above in FIG. 4 is applied. A signal is generated and this DC bias signal is supplied to adder circuit 58.

In this adder circuit 58, the search drive signal and the DC bias signal are added to form a search drive signal/DC bias signal addition signal, and this addition signal is supplied to the tracking servo actuator drive circuit 59.

This tracking servo actuator drive circuit 59 supplies a drive voltage based on the search drive signal/DC bias signal addition signal to the coil 39 of the tracking servo actuator 32, so that the drive force of this actuator 32 causes the movable part 38 to , thus the light spot 16 moves towards the target track. At this time, since the spring stress is canceled by the DC bias voltage corresponding to the DC bias signal,
The moving speed of this light spot 16 corresponds to the search drive signal.

In the movement detection circuit 54, a movement speed is detected from the number of crossings of the recording track by the optical spot 16 per unit time, and a movement speed signal representing this movement speed is supplied to the search servo circuit 56. In this search servo circuit 56, the search drive signal is always corrected based on the moving speed signal, so that the light spot 16 reaches the target track in the shortest possible time, and the above-described search operation is performed. At this time, a track crossing number signal representing the number of crossings of the recording track by the optical spot 16 is supplied from the movement detection circuit 54 to the track address generating circuit 55. The current position signal is updated based on the signal, and this current position signal always corresponds to the current position even during the search operation. Therefore, the DC bias signal corresponds to this current position, and the spring stress can be accurately canceled.

Further, based on the current position signal, the drive CPU 5
1, the switching terminal of the electronic switch 52 is connected to the upper input terminal by the tracking pull-in signal outputted at the timing immediately before the optical spot 16 reaches the target track, so that the tracking servo signal is connected to the addition terminal. A circuit 58 is provided.

As mentioned above, the tracking servo signal generated in the tracking servo circuit 53 and representing the deviation of the optical spot 16 from the center of the recording track is added to the DC bias signal in the adding circuit 58, and the tracking servo signal is added to the DC bias signal. This becomes a DC bias signal addition signal, and this addition signal is supplied to the tracking servo actuator drive circuit 59. This tracking servo actuator drive circuit 59 supplies a drive voltage based on the tracking servo signal/DC bias signal addition signal to the tracking servo actuator 32, thereby performing the above-described tracking servo operation. At this time, since the spring stress is canceled by a DC bias voltage corresponding to the DC bias signal, this tracking servo operation corresponds to the tracking servo signal.

Further, in the drive CPU 51, arrival at the target track is confirmed based on the current position signal from the track address generation circuit 55.

The tracking control device 50 according to an embodiment of the present invention having the above configuration includes the tracking servo actuator 32 of the above-mentioned new one-stage control system, which is incorporated in the optical recording/reproducing device 6 used in the magneto-optical disk device 1. For this control, the movement detection circuit 54 and track address generation circuit 55 constantly detect the current position of the optical spot 16, constantly update the current position signal, and adjust the DC bias according to this current position signal. Since the stress of the leaf springs 41A and 41B is canceled by the voltage, the above-mentioned search operation and tracking servo operation are not affected by the stress of the leaf spring, and are performed according to the search drive signal and the tracking servo signal. Become a thing,
Highly accurate control becomes possible.

In FIG. 4, the relationship between the moving amount of the movable portion 38 of the tracking servo actuator 32 and the spring stress is explained by taking as an example a case where there is a proportional relationship, but the case with other spring characteristics is also described. Of course, the control device of the present invention can be applied. Further, even if the electromagnetic force of the coil 39 of the actuator 32 changes due to variations in the strength of the magnetic field in the air gap depending on the position, the control device of the present invention can be similarly applied.

Furthermore, the mechanical stability point of this actuator 32 is
As described above, the case where the recording area 3 is set to be located at the center in the radial direction has been described, but the control device of the present invention is also applicable to cases where the recording area is set at a position other than this. .

(Effects of the Invention) The tracking control device of the present invention having the above configuration has the following features:
A tracking servo that is incorporated into an optical recording/reproducing device consisting of a fixed part unit and a movable part unit, includes a leaf spring that allows the movable part of the movable part unit to move only in the tracking direction, and performs a tracking servo operation and a search operation. When controlling the actuator, the current position of the light spot is always detected by the current position detection means, and the stress in the leaf spring is canceled by the DC bias voltage according to this current position by the DC bias generation means. Since the tracking servo operation and the search operation can be performed without being affected by the stress of the leaf spring, the above-mentioned type of tracking servo actuator can be controlled with high precision.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the tracking control device of the present invention, FIG. 2 is an explanatory diagram of recording and reproducing operations of an example of a small magneto-optical disk device incorporating the control device of FIG. 1, and FIG. is a structural diagram showing an example of the actuator in Fig. 2, the same figure (^) is a perspective view showing the state with the base removed, the same figure (B) is a top view of the same figure (^), the same figure <C>
is a side sectional view, FIG. 4 is a graph showing the relationship between the amount of movement of the movable part and spring stress in the tracking servo actuator of FIG. 3, and FIG. 5 is a block diagram showing an example of a conventional tracking/feed control device. FIG. 6 is an explanatory diagram of the recording and reproducing operation of an example of a small magneto-optical disk device in which the control device of FIG. 5 is incorporated. 1... Small magneto-optical disk device, 2... Small magneto-optical disk (optical disk), 3...
Recording area, 6... Optical recording/reproducing device, 6-1... Fixed part unit, 6-2... Movable part unit, 7... Laser diode (light emitting element) 10... Standing prism, 11... Objective lens, 14A, 14B.
... Photodiode (light receiving element), 16... Light spot, 20... Focus and tracking servo actuator, 32... Tracking servo actuator, 33.
... Fixed part, 34... Magnet (field part), 36.
...Yoke (field part), 38...Movable part, 3...
Coil, 41A, 41B... Leaf spring, 50... Tracking control device, 54... Movement detection circuit (current position detection means), 55.
...Track address generation circuit (current position detection means), 57...DC bias signal generation circuit (DC bias generation means), 5...Tracking servo actuator drive circuit (DC bias generation means).

Claims (1)

[Claims] a fixed part unit including at least a light emitting element that emits a laser beam and a light receiving element that obtains a detection signal from the reflected light from the optical disk; a rising prism that converts the optical axis of the light beam from the fixed part unit to a right angle upward direction; It is incorporated into an optical recording/reproducing device comprising a movable unit disposed on the optical axis of the light beam converted upward at right angles and having an objective lens disposed opposite to the recording area of the optical disk. A tracking control device comprising a leaf spring that allows a movable part to move only in the tracking direction, and controlling a tracking servo actuator that performs a tracking servo operation and a search operation by moving a light spot by the objective lens, the tracking control device comprising: A current position detection means that constantly detects the current position of the light spot outputs a current position signal, and a DC bias generation means that outputs a DC bias voltage based on the current position signal cancels the stress corresponding to the displacement of the leaf spring. A tracking control device characterized by: