JP2000149281A - Optical information recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording/reproducing device capable of effectively suppressing an unwanted displacement of an objective lens with a simple and inexpensive configuration. SOLUTION: This recording/reproducing device is provided with an optical head 20 having the objective lens 1, a tracking drive means having at least two pieces of tracking coils 7a, 7b, and a means for detecting the position of the objective lens 1 with respect to the optical head 20. In such a case, the position detecting means is provided with a moving speed detection circuit 38 for differentially amplifying speed electromotive forces respectively generated in the tracking coils 7a, 7b due to the displacement of the objective lens 1 in the tracking direction and detecting the moving speed of the objective lens 1 and a moving amount detection circuit 39 for detecting the moving amount of the objective lens 1 to/from the optical head 20 based on the output of the moving speed detection circuit 38, thereby feeding back the output of the moving amount detection circuit 39 to the tracking coils 7a, 7b and controlling the displacement of the objective lens 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing device such as an optical disk device and an optical card device.

[0002]

2. Description of the Related Art For example, in an optical disk apparatus, an optical head having an objective lens is moved in a radial direction of an optical disk by a seek means such as a voice coil motor (VCM) to access a desired information track.
Tracking control is performed by moving the objective lens in the tracking direction across the information track on the optical head by the tracking driving means so that the light spot formed on the optical disk via the objective lens follows the desired information track. I have.

In such an optical disk device, in order to perform tracking control, it is necessary to support the objective lens in the optical head so as to be displaceable in the tracking direction. Systems, shaft sliding systems and the like have been proposed.

When the objective lens is driven in the tracking direction by the tracking driving means, it is preferable to drive the objective lens in the tracking direction around the neutral position of the support means in order to stably perform the tracking control. Also, when the optical head accesses a desired information track of the optical disk by the seek means, it is necessary to position the objective lens at the neutral position of the support means while suppressing the deflection of the objective lens due to the movement of the optical head. It is preferable from the viewpoint of tracking control.

[0005] From the above, there is conventionally known a device which optically detects the position of the objective lens with respect to the support means and feeds back the position detection signal to a tracking coil to suppress the shake of the objective lens. ing.
Further, as disclosed in Japanese Patent Application Laid-Open No. 8-1066641, a coil for detecting a speed electromotive force is provided separately from the tracking coil, and an objective lens is detected based on the speed electromotive force detected by the coil for detecting the speed electromotive force. Of the type described above, the amount of movement of the objective lens relative to the optical head is detected, and the amount of movement is fed back to the tracking coil to suppress the shake of the objective lens. As disclosed in JP-A-6-333242, Is selectively used as a speed electromotive force detection coil to sample and hold the speed electromotive force generated when the tracking coil is not energized, and supply the held signal to the tracking coil so as to suppress the vibration of the objective lens. Is known.

[0006]

However, the method of optically detecting the position of the objective lens as described above requires a light source and a light-receiving element for position detection, so that the number of parts is large and the structure is large. However, there is a problem that the cost increases and the cost increases. Also, JP-A-8-10
Even in the device disclosed in Japanese Patent No. 6641, since the speed electromotive force detection coil is provided separately from the tracking coil, the number of components is increased, and the magnetic circuit for the tracking coil and the speed electromotive force detection coil is increased. However, there is a problem that the configuration becomes complicated and the cost increases.

On the other hand, in the one disclosed in JP-A-6-333242, the tracking coil is selectively used as a speed electromotive force detecting coil. However, in this conventional example, since the back electromotive force generated when the driving of the tracking coil is stopped is sufficiently suppressed, the speed electromotive force generated in the tracking coil is sampled and held. This causes a problem that the shake of the objective lens cannot be suppressed with high accuracy.

The present invention has been made in view of the above-mentioned conventional problems, and has an optical information recording / reproducing apparatus capable of effectively suppressing undesired shake of an objective lens with a simple and inexpensive configuration. The purpose is to provide.

[0009]

In order to achieve the above object, an invention according to a first aspect is directed to an optical head having an objective lens, and tracking for controlling tracking so that the objective lens follows the desired information track. In an optical information recording / reproducing apparatus having a driving unit and a position detecting unit for detecting a position of the objective lens with respect to the optical head, the tracking driving unit includes at least two tracking coils, and And a magnetic field generating means for applying a magnetic field by applying a magnetic field. When the objective lens is displaced in one of the tracking directions, the magnetic field acting on one of the tracking coils decreases and the magnetic field acting on the other tracking coil increases. When the objective lens is displaced in the other direction in the tracking direction, The magnetic field acting on the tracking coil is increased, and the magnetic field acting on the other tracking coil is decreased, and the position detecting means is configured to displace the one of the ones with the displacement of the objective lens in the tracking direction. A moving speed detecting circuit for differentially amplifying a speed electromotive force generated in each of the tracking coil and the other tracking coil to detect a moving speed of the objective lens, and detecting the moving speed of the objective lens based on an output of the moving speed detecting circuit A moving amount detecting circuit for detecting a moving amount with respect to the optical head, wherein an output of the moving amount detecting circuit is fed back to the at least two tracking coils to suppress displacement of the objective lens. It is characterized by having comprised.

Further, according to the present invention, there is provided an optical head having an objective lens, tracking drive means for performing tracking control so that the objective lens follows the desired information track, and the optical head of the objective lens. In the optical information recording / reproducing apparatus having a position detecting means for detecting a position with respect to the tracking coil, the tracking driving means has at least two tracking coils and a magnetic field generating means for applying a magnetic field to these tracking coils. And the position detecting means selectively differentially amplifies a velocity electromotive force generated in one of the at least two tracking coils in accordance with the displacement of the objective lens in the tracking direction. A moving speed detecting circuit for detecting the moving speed of the objective lens And a movement amount detection circuit for detecting a movement amount of the objective lens with respect to the optical head based on an output of the degree detection circuit, and an output of the movement amount detection circuit is provided for the at least two tracking coils. The objective lens is configured to be fed back to the other tracking coil to suppress the displacement of the objective lens.

Further, according to a third aspect of the present invention, there is provided an optical head having an objective lens, seek means for accessing the optical head to a desired information track of a recording medium, and the objective lens following the desired information track. In an optical information recording / reproducing apparatus having tracking driving means for performing tracking control so as to perform the tracking control, and position detecting means for detecting a position of the objective lens with respect to the optical head, the tracking driving means has at least two tracking coils. And a magnetic field generating means for applying a magnetic field to these tracking coils, wherein the position detecting means is configured to detect a position of the at least two tracking coils along with a displacement of the objective lens in a tracking direction. Velocity electromotive force generated in at least one of the tracking coils A moving speed detecting circuit that dynamically amplifies and detects a moving speed of the objective lens; and a moving amount detecting circuit that detects a moving amount of the objective lens with respect to the optical head based on an output of the moving speed detecting circuit. The output of the movement amount detection circuit is fed back to the seek means to suppress the displacement of the objective lens.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a configuration of an example of an optical head to which the present invention can be applied.
The optical head 20 is of a four-wire type, and a lens holder 2 for holding the objective lens 1 has four parallel wires 3 extending in, for example, a tangential (x) direction of an optical disk (not shown). It is supported on a substrate 5 attached to a base 4 made of a magnetic material via a movable member in a tracking (y) direction and a focusing (z) direction.

A focus coil 6 is wound around the lens holder 2 so as to wind the optical axis of the objective lens 1, and four flat tracking coils 7a, 7b are mounted on the focus coil 6. And 8a, 8b (8
b is not shown). Here, the tracking coils 7a and 7b are provided such that one coil side (operating side) extending in the z direction is located on one end surface of the lens holder 2 in the x direction, and the tracking coils 8a and 8b are
One coil side (operating side) each extending in the z direction
Is provided on the other end surface of the lens holder 2 in the x direction.

Outer yokes 11a and 11b are integrally formed on the base 4 so as to face the x-direction end surfaces of the lens holder 2 and are made to enter the lens holder 2 so as to face the outer yokes 11a and 11b, respectively. The inner yokes 12a and 12b are integrally formed. In addition, outer yoke 1
Permanent magnets 13a, 13b constituting magnetic field generating means are provided on the lens holder 2 side of 1a, 11b, respectively, so that the permanent magnet 13a applies a magnetic field to the focus coil 6 and the tracking coils 7a, 7b. 13b causes a magnetic field to act on the focus coil 6 and the tracking coils 8a and 8b.
The substrate 5 is attached to the outer yoke 11b on the side opposite to the permanent magnet 13b.

Thus, the focus coils 6 and 2
The two permanent magnets 13a, 13b constitute two sets of focus driving means, and the tracking coils 7a, 7b
And permanent magnets 13a, and tracking coils 8a and 8
b and the permanent magnet 13b constitute two sets of tracking driving means, and supply power to the focus coil 6,
The objective lens 1 is driven integrally with the lens holder 2 in the z-direction by electromagnetic interaction with magnetic fields from the permanent magnets 13a, 13b, and the tracking coils 7a, 7b and 8a, 8b
To the permanent magnets 13a, 13b
The objective lens 1 is driven integrally with the lens holder 2 in the y direction by electromagnetic interaction with a magnetic field from the lens.

FIG. 2 shows a schematic configuration of an optical disk device having the optical head 20 shown in FIG. The optical head 20 is mounted on a carriage 21, and the carriage 21 is driven by a seek signal from a control circuit (not shown).
The optical head 20 is moved in the radial direction of the optical disk 24 by being driven by the VCM 23 through the CM drive circuit 22, and the optical head 20 is fixed to the fixed optical system 2.
From 5, a recording or reproducing light beam is made to enter.

The fixed optical system 25 includes a semiconductor laser 26,
A collimator lens 27, a beam splitter 28, and a photodetector 29 are provided, and a recording or reproducing light beam from the semiconductor laser 26 is guided to the optical head 20 via the collimator lens 27 and the beam splitter 28. The light beam guided to the optical head 20 is reflected by a prism 31 provided on the optical head 20 and irradiates the optical disk 24 in a spot shape by the objective lens 1.

The return light reflected by the optical disk 24 passes through the objective lens 1, the prism 31, and the beam splitter 28, is received by the photodetector 29, and is output to the signal processing circuit 32 based on the output thereof. Tracking error signal TE and focusing error signal F
E, and the tracking error signal TE is passed through the tracking (TR) drive circuit 33 to the tracking coils 7a,
7b and 8a, 8b are supplied to perform tracking control, and a focusing error signal FE is supplied to a focus coil 6 via a focus driving circuit (not shown) to perform focus control. Note that FIG.
Here, the illustration of the focus coil 6 is omitted.

In the first embodiment of the present invention, in the optical head 20 shown in FIG. 1, the magnetic field distribution of the permanent magnets 13a and 13b and the tracking coils 7a, 7b and 8a,
8b is appropriately set to the mounting position on the lens holder 2,
When the lens holder 2 is displaced in one of the y directions, the magnetic field acting on the tracking coils 7a, 8a on one side decreases, the magnetic field acting on the tracking coils 7b, 8b on the other side increases, and When the lens holder 2 is displaced in the other direction in the y direction, the magnetic field acting on the tracking coils 7a, 8a on one side increases and the magnetic field acting on the tracking coils 7b, 8b on the other side decreases. To be configured.

FIG. 3 shows a configuration of a main part of the first embodiment. In this embodiment, the TE signal is subtracted from the subtractor 3
5 and a phase compensating circuit 36 to supply the TR driving circuit 33 with a required driving current corresponding to the TE signal from the TR driving circuit 33 to the tracking coils 7a, 7b, 8a, 8b connected in series. . The electromotive force generated in each of the tracking coils 7a and 7b is supplied to a moving speed detecting circuit 38 to detect a speed signal, and the speed signal is integrated by an integrator 39 constituting a moving amount detecting circuit to obtain a moving amount. The displacement signal is converted into a corresponding displacement signal, and the displacement signal is fed back to the subtraction circuit 35.
b, 8a and 8b.

The moving speed detecting circuit 38 includes a differential amplifier 41 for differentially amplifying the electromotive force generated in the tracking coil 7a.
And a differential amplifier 42 for differentially amplifying the electromotive force generated in the tracking coil 7b, and a differential amplifier 43 for differentially amplifying the outputs of the differential amplifiers 41 and 42.

In this embodiment, when a drive current is supplied to the tracking coils 7a, 7b, 8a, 8b, a counter electromotive force of the same polarity is generated in each coil, but the lens holder 2 (see FIG. 1) is moved in the y direction. When displaced, the magnetic fields acting on the tracking coils 7a and 7b and 8a and 8b respectively increase on the one hand and decrease on the other hand,
In the tracking coils 7a and 7b and 8a and 8b, velocity electromotive forces having polarities opposite to each other are generated according to the displacement of the lens holder 2 in the y direction.

Therefore, in the moving speed detecting circuit 38, the electromotive forces generated in the tracking coils 7a and 7b are differentially amplified by the differential amplifiers 41 and 42, respectively, and the outputs of the differential amplifiers 41 and 42 are output by the differential amplifier 43. If the differential amplification is performed, a large speed electromotive force in which the back electromotive force is canceled out, that is, a speed signal can be obtained. This speed signal is converted into a displacement signal corresponding to the movement amount by the integrator 39, and the tracking coil 7a , 7b, 8a, and 8b, unwanted vibration of the objective lens 1 can be effectively suppressed in real time during seek control or tracking control after seek.

FIG. 4 shows a configuration of a main part of a second embodiment of the present invention. In this embodiment, in the optical disk device shown in FIG. 2, one of the four tracking coils 7a, 7b, 8a, 8b is selectively used as a speed detecting coil in FIG. Also, the moving speed of the objective lens 1 is detected, and undesired shake of the objective lens 1 is prevented based on a displacement signal corresponding to the moving speed. Therefore, a changeover switch 45 is provided on the output line of the TR drive circuit 33,
When the changeover switch 45 is connected to the contact 45a, the drive current from the TR drive circuit 33 is supplied to the tracking coils 7a, 7b, 8a, 8b, and the changeover switch 45 is connected to the contact 45b. At the time, the driving current from the TR driving circuit 33 is supplied to the tracking coils 7b, 8
a, 8b, and the electromotive force generated in the tracking coil 7a is supplied to the moving speed detection circuit 46.

The changeover switch 45 and the moving speed detection circuit 46 are controlled by a control circuit (not shown), and when the changeover switch 45 is connected to the contact 45b side and no drive current is supplied from the TR drive circuit 33 to the tracking coil 7a. The speed electromotive force generated in the tracking coil 7a is detected by a moving speed detecting circuit 46 to obtain a speed signal, and the speed signal is integrated by an integrator 39 to be converted into a displacement signal corresponding to the moving amount. Is fed back to the subtraction circuit 35, and the phase compensation circuit 36 and the TR drive circuit 33
To the tracking coils 7b, 8a, 8b.

As described above, the tracking coil 7a is selectively used as a speed detecting coil, and the speed electromotive force generated when the drive current is not supplied from the TR drive circuit 33 to the tracking coil 7a is detected to detect the speed. If a signal is obtained, no back electromotive force is generated in the tracking coil 7a due to the drive current.
6 can be easily configured using one differential amplifier 47, whereby the objective lens 1 can be used at the time of seek or tracking control after seek as in the first embodiment.
Can be effectively suppressed in real time.

In the second embodiment, there is no need to cancel the back electromotive force due to the drive current as in the first embodiment, so that the tracking coils 7a, 7b, 8a, 8b
May be arranged such that their working sides are located in a uniform magnetic field over the moving range of the objective lens 1 in the y direction.

FIG. 5 shows a configuration of a main part of a third embodiment of the present invention. In this embodiment, the displacement signal of the objective lens 1 obtained from the integrator 39 in the first embodiment is supplied to the VCM coil 23a constituting the VCM 23 via the phase compensation circuit 51 and the VCM drive circuit 22,
Thus, undesired shake of the objective lens 1 is suppressed in real time.

According to this embodiment, tracking can be performed by the two-stage servo of the tracking coils 7a, 7b, 8a, 8b and the VCM 23, so that more stable tracking control can be performed.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified or changed. For example, in the first and third embodiments, the speed signals are detected by using the tracking coils 7a and 7b as well, but other sets of the tracking coils 8a and 8b are used.
b, the speed signal is detected, or the tracking coils 7a, 7b and the tracking coils 8a, 8b
It is also possible to detect the speed signals in both sets and add the speed signals. Also, a tracking coil 7a located on a diagonal line of the lens holder 2
And 8b, and 7b and 8a as a set, and the speed signal may be detected from one or both sets. In this way, rolling of the objective lens 1 with the swing direction in the x direction can also be suppressed.

In the third embodiment, a displacement signal of the objective lens 1 is detected by applying the second embodiment, and this displacement signal is supplied to the VCM coil 23a to perform two-step servo for tracking. You can also. In this case, as described in the second embodiment, the working sides of the tracking coils 7a, 7b, 8a, 8b are located in a uniform magnetic field over the moving range of the objective lens 1 in the y direction. It can also be arranged as follows.

Further, the present invention is not limited to the optical head 20 shown in FIG. 1, but various optical information recording devices such as an optical disk device and an optical card device equipped with a known optical head having at least two tracking coils. / It can be effectively applied to a playback device.

[0033]

As is apparent from the above description, according to the present invention, an undesired shake in the tracking direction of the objective lens can be effectively suppressed with a simple and inexpensive structure which also serves as a tracking coil. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an example of an optical head to which the present invention can be applied.

FIG. 2 is a diagram showing a schematic configuration of an optical disk device having the optical head shown in FIG.

FIG. 3 is a diagram showing a configuration of a main part of the first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a main part of the second embodiment.

FIG. 5 is a view showing a configuration of a main part of the third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 3 Wire 4 Base 5 Substrate 6 Focusing coil 7a, 7b, 8a, 8b Tracking coil 11a, 11b Outer yoke 12a, 12b Inner yoke 13a, 13b Permanent magnet 20 Optical head 21 Carriage 22 VCM drive circuit 23 VCM Reference Signs List 24 optical disk 25 fixed optical system 26 semiconductor laser 27 collimator lens 28 beam splitter 29 photodetector 31 prism 32 signal processing circuit 33 tracking (TR) drive circuit 35 subtraction circuit 36 phase compensation circuit 38 moving speed detection circuit 39 integrator 41, 42 , 43 Differential amplifier 45 Changeover switch 46 Moving speed detection circuit 47 Differential amplifier 51 Phase compensation circuit

Claims (3)

[Claims] An optical head having an objective lens; tracking drive means for performing tracking control so that the objective lens follows the desired information track; and position detecting means for detecting a position of the objective lens with respect to the optical head. An optical information recording / reproducing apparatus having: a tracking driving unit having at least two tracking coils and a magnetic field generating unit for applying a magnetic field to the tracking coils; When the objective lens is displaced in the other direction in the tracking direction, the magnetic field acting on one of the tracking coils decreases and the magnetic field acting on the other tracking coil increases. The magnetic field acting on the tracking coil increases,
The magnetic field acting on the other tracking coil is configured to decrease, and the position detecting means is generated in the one tracking coil and the other tracking coil with displacement of the objective lens in a tracking direction. A moving speed detecting circuit for differentially amplifying a speed electromotive force to detect a moving speed of the objective lens; and a moving amount detecting device for detecting a moving amount of the objective lens with respect to the optical head based on an output of the moving speed detecting circuit. Wherein the output of the movement amount detection circuit is fed back to the at least two tracking coils to suppress the displacement of the objective lens. Playback device. 2. An optical head having an objective lens, tracking driving means for performing tracking control so that the objective lens follows the desired information track, and position detecting means for detecting a position of the objective lens with respect to the optical head. An optical information recording / reproducing apparatus comprising: a tracking drive unit configured to include at least two tracking coils and a magnetic field generation unit that applies a magnetic field to the tracking coils; The means selectively differentially amplifies a speed electromotive force generated in one of the at least two tracking coils as the objective lens is displaced in the tracking direction, thereby increasing a moving speed of the objective lens. Based on the moving speed detecting circuit to be detected and the output of the moving speed detecting circuit, And a movement amount detection circuit for detecting a movement amount of the objective lens with respect to the optical head, and an output of the movement amount detection circuit is fed back to the other of the at least two tracking coils. An optical information recording / reproducing apparatus, wherein the optical information recording / reproducing apparatus is configured to suppress the displacement of the objective lens. 3. An optical head having an objective lens, seek means for accessing the optical head to a desired information track on a recording medium, and tracking drive for performing tracking control so that the objective lens follows the desired information track. Means, and an optical information recording / reproducing apparatus having a position detecting means for detecting a position of the objective lens with respect to the optical head, wherein the tracking drive means comprises at least two tracking coils, and Magnetic field generating means for applying a magnetic field, wherein the position detecting means is generated in at least one of the at least two tracking coils with a displacement of the objective lens in a tracking direction. Differential amplification of velocity electromotive force A moving speed detecting circuit for detecting a moving speed; and a moving amount detecting circuit for detecting a moving amount of the objective lens with respect to the optical head based on an output of the moving speed detecting circuit. An optical information recording / reproducing apparatus, wherein an output of a circuit is fed back to the seek means to suppress displacement of the objective lens.