JPH10312565A - Optical-disk driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical-disk driving apparatus which can correct a bad influence in a scanning operation due to an inclination in the outer circumferential position or the arbitrary position of an optical disk. SOLUTION: In an optical-disk driving apparatus, information is recorded in such a way that a track groove on the information recording face of an optical disk is scanned by a light spot via an objective lens at an optical pickup. In the optical-disk driving apparatus, offset amounts of a push-pull signal as a kind of a tracking error signal are detected by a two-split PD 1 and a differential amplifier 2 in regions in which respective track groove do not exist in the inner circumference of the optical disk and in the outer circumference of the optical disk. Then, the relative posture angle with reference to the information recording face of the optical disk of the objective lens at the optical pickup is adjusted by an inclination actuator 15 in such a way that the offset amount, in the inner circumference of the optical disk and in the outer circumference, which are detected by the two-split PD 1 and the differential amplifier 2 become equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical disk drive.

[0002]

2. Description of the Related Art The configuration of a conventional magneto-optical recording apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-231930.
That is, as shown in FIGS. 6 and 7, reflected light from the optical disk 101 based on irradiation light from the light emitting element 111 is received by the two light receiving elements 112a and 112b. And 2
The difference between the light receiving amounts of the light receiving elements 112a and 112b is obtained by the differential amplifier 113, and the output of the differential amplifier 113 is supplied to the motor 115 in the tilt mechanism 107 via the amplifier 114 as the amount of inclination.

In such a configuration, C and C 'shown in FIG.
When the slider base 109 that can move in the direction moves from the position (a) in the C ′ direction and reaches a tilted portion (position (b)) of the outer peripheral portion of the optical disc 101, it tilts according to the output of the optical sensor 110. The mechanism 107 operates to rotate the optical system body 106 clockwise about the rotation fulcrum 108 in FIG. 6 and stops the operation at a position where the optical axes B and B ′ are substantially perpendicular to the pit surface of the optical disc 101. .

As described above, following the static warpage of the optical disk 101, the optical axes B and B 'are controlled so that they are always substantially perpendicular to the pit surface.

In the above-described conventional apparatus, the optical axes B and B 'of the irradiation light are easily shifted due to the shift of the axis between the light emitting element 111 and the lens 105 in the optical sensor 110. There are problems that it is difficult to maintain the perpendicularity to the reference plane and that the inclination of the optical disc 101 cannot be detected accurately.

The light emitting element 111 and the light receiving element 112
Since a and 112b are expensive, there is also a problem that the cost of the entire apparatus increases.

Japanese Patent Application Laid-Open No. 60-231930 also discloses a magneto-optical recording device shown in FIG. This magneto-optical recording apparatus includes a so-called focus error detecting means 13.
0, and a position detecting means 137 for detecting the position of the optical pickup with respect to the optical disc 101 in the radial direction of the optical disc 101. The output of the position detecting means 137 and the output of the focus error detecting means 130 are calculated. The tilt of the optical axis of the objective lens 105 in the optical pickup with respect to the optical disk 101 is adjusted in accordance with the calculation output. In FIG. 8, 131 is a quadrant detector, 132 is an error amplifier, 13
5 is a low-pass filter, and 136 is an amplifier.

In the magneto-optical recording apparatus shown in FIG. 8, the slider base 109 moves from the position (a) to the position (b) as in the case shown in FIG. Then, the working distances A and A1 between the optical disc 101 and the objective lens 105 change,
The objective lens 105 is further driven by the focus servo system by the amount of the change, and the objective lens 105 and the optical disc 1 are moved.
The distance to 01 is kept constant.

Thus, the optical system is always kept in focus. When the objective lens 105 is driven, the driving unit 13
3 based on the current flowing through the movable coil 134,
Since the amount of movement of the objective lens 105 in the optical axis direction is obtained from both ends of the optical disk 101, the amount of movement is detected as the amount of inclination Y of the optical disk 101.

On the other hand, the position detecting means 137 detects the position information X of the objective lens 105 with respect to the optical disk 101 in the disk radial direction.

The position information X and the tilt amount Y of the optical disk 101 are approximated by a function, and the tilt angle A of the optical disk 1 is set to a differential value d / dx · f (X) of the function Y = f (X). The calculation is performed by the calculation circuit 138. And the arithmetic circuit 13
The tilt signal calculated in step 8 is supplied to the motor 115, and the optical system body 106 is rotated with respect to the slider base 109 by the tilt angle, whereby the objective lens 10 is rotated.
The optical axis 5 is controlled so as to be perpendicular to the information recording surface of the optical disc 101.

[0012]

The principle problem of the tilt servo in the conventional system is that Y = f based on the position information X in the radial direction of the optical disc and the tilt amount Y of the optical disc 1.
Considering the function of (X), the inclination angle A of the optical disc 101
In order to perform the calculation of d / dx · f (X), the inclination angle A of the optical disc 101 cannot be obtained unless there is continuous data on the position information X and the inclination amount Y.

When an audio signal or a video signal is reproduced, since a spiral track is continuously scanned, the position information changes with time, continuous data is obtained, and the differential data is obtained by differentiating them. Optical disk 10
It is possible to obtain a tilt angle A of 1.

However, a CD for computer data purposes
-In the case of the optical disk 101 such as a ROM, continuous data is not obtained because a random optical disk position is accessed.
As a result, it is difficult to obtain the correction angle while reproducing.

The present invention has been made in view of the above circumstances, and can correct an adverse effect due to a tilt at an outer peripheral position of an optical disc or an arbitrary position even when there is no continuous data on position information and a tilt amount. It is an object of the present invention to provide a simple optical disk drive.

[0016]

According to the first aspect of the present invention,
In an optical disk drive device for performing information scanning by scanning a track groove on an information recording surface of an optical disk with an optical spot through an objective lens in an optical pickup, an area without track grooves on an inner circumference of the optical disk and an outer circumference of the optical disk. An offset amount detecting means for detecting an offset amount of a push-pull signal which is a kind of tracking error signal, and an optical pickup in the optical pickup such that the offset amounts on the inner and outer circumferences of the optical disk detected by the offset amount detecting means are equal. And an angle adjusting means for adjusting a relative attitude angle of the objective lens with respect to the information recording surface of the optical disk.

According to a second aspect of the present invention, there is provided an optical disc driving apparatus for recording information by scanning a track groove on an information recording surface of an optical disc with an optical spot through an objective lens in an optical pickup. An offset amount detecting means for detecting an offset amount of a push-pull signal, which is a kind of tracking error signal, in an area where there is no track groove on the outer circumference of the optical disc; and an inner and outer circumference of the optical disc detected by the offset amount detecting means. Calculating means for calculating the amount of tilt of the outer circumference of the optical disk with respect to the inner circumference based on the offset amount, and obtaining the amount of tilt correction for each optical disk position scanned by the light spot in an area where a track groove exists, based on the obtained amount of tilt; And the tilt correction amount obtained by this calculation means. It is characterized in that it has a, and angle adjusting means for adjusting the relative orientation angle with respect to the information recording surface of the optical disc of the objective lens in the optical pickup for each disc position scanned Te.

According to a third aspect of the present invention, in the optical disk drive according to the first or second aspect, the offset amount detecting means includes a two-division photodetector divided in a radial direction of the reflected light from the optical disk; A differential amplifier that obtains a push-pull signal depending only on the tilt of the optical disk based on a detection signal of a photodetector.

Hereinafter, the present invention will be described in more detail. According to the present invention, during the initialization operation after the power is turned on, the offset amount detecting means detects the offset amount of the push-pull signal in the area (mirror portion) where there is no track groove on the inner circumference and the outer circumference of the optical disk, and the angle adjusting means Thereby, the relative attitude angle of the objective lens in the optical pickup with respect to the information recording surface of the optical disk is adjusted so that the offset amount in the outer mirror unit becomes the same value as the offset amount in the inner mirror unit. To correct the adverse effect due to the inclination of

Further, according to the present invention, the offset amount detecting means detects the DC offset amount of the push-pull signal in the area (mirror portion) where there is no track groove on each of the inner and outer circumferences of the optical disk, and the calculating means detects the offset amount. An inclination amount of the outer circumference of the optical disc with respect to the inner circumference is determined based on the offset amounts of the inner circumference and the outer circumference of the optical disk detected by the detection means, and scanning is performed by the light spot in an area where a track groove exists based on the calculated inclination amount. A tilt correction amount is obtained for each of the determined optical disk positions. Further, the relative attitude angle of the objective lens in the optical pickup with respect to the information recording surface of the optical disk is adjusted for each optical disk position scanned according to the tilt correction amount obtained by the calculating means. Thereby, it is possible to correct the adverse effect due to the inclination at an arbitrary position on the information recording surface of the optical disc.

Further, according to the present invention, as the offset amount detecting means, a two-divided photodetector divided in a radial direction of the reflected light from the optical disk, and a tilt of the optical disk based on a detection signal of the two-divided photodetector. And a differential amplifier that obtains a push-pull signal depending only on the above-described function.

[0022]

Embodiments of the present invention will be described below in detail.

FIG. 1 shows an optical disk drive according to an embodiment of the present invention, which comprises a spindle motor 11, a turntable 12, an optical disk clamper 13, an optical pickup 14, and a tilt actuator 15 constituting angle adjusting means. The optical disk 10 is driven to rotate by the spindle motor 11.

In FIG. 1, the optical pickup 14,
The tilt actuator 15 is in a state of being located at a mirror portion on the inner periphery of the optical disc 10 and includes an optical pickup 14 ′,
The tilt actuator 15 'shows a state where the tilt actuator 15' is located at a mirror portion on the outer periphery of the optical disk 10.

FIG. 2 shows the structure of the optical pickup 14 and the tilt actuator 15. An actuator section 42 for holding an objective lens 41 is mounted on a pickup body 43, and is rotated by a carriage 44 around a rotation shaft 45. The optical pickup 14 is supported at two points as much as possible, and the tilt of the optical pickup 14 is adjusted by rotating about the rotation shaft 45. Carriage 4
A servo motor (or a pulse motor) 46 is mounted on the optical pickup 4, and is connected to the optical pickup 14 by a screw screw 47. The rotation of the screw screw 47 drives the optical pickup 14 about a rotation shaft 45 as a rotation center. Below the carriage 44, four bearings 48 are attached so that the carriage 44
9 can be slid.

In the control system of the optical disk drive shown in FIG. 3, the push-pull signal detecting two-divided PD (photodiode) 1 constituting the offset amount detecting means is provided to an optical pickup 14 which is a recording medium (not shown). A condensed spot emitted from the optical pickup 14 is reflected by the surface of the optical disc 10,
The return light is received by the split PD1. 2-split PD1
Are divided in a direction in which a differential signal in the radial direction of the optical disk 10 is obtained, and each signal is input to the differential amplifier 2 to obtain a push-pull signal.

Generally, a push-pull signal is used as a tracking error signal, is generated by being diffracted by a track groove, and when the light spot is located at the center of the track groove, the return light to the two-divided PD 1 is divided by a dividing line. When the light spot deviates from the center of the track groove, the return to the two-divided PD1 becomes an asymmetrical diffraction pattern, and the diffraction pattern deviates from the track groove in each of the left and right directions. Since it occurs on the contrary, it is used as a tracking error signal.

In the case where the information recording surface of the optical disk 10 which is the reflection surface has an inclination, the push-pull signal has a bias in the intensity distribution of the return light and appears as an offset voltage. Therefore, when there is no track groove, a signal corresponding to only the tilt of the optical disk appears.

The output of the differential amplifier 2 passes through a low-pass filter 3 to remove high-frequency noise, is converted into a digital signal by an A / D converter 4, and is input to an arithmetic processing unit 5. The arithmetic processing unit 5 outputs a movement instruction to a CPU of an access control system (not shown), whereby a series of sequences shown in FIG. 4 is executed. The arithmetic processing unit 5 supplies a digital signal to the D / A converter 6 and converts the digital signal into an analog value. The analog value is input to the driver 7 to drive the tilt actuator 15.

FIG. 4 shows a flowchart of a sequence performed by the arithmetic processing unit 5. The processing shown in FIG. 4 is performed as one of the operations in the initialization immediately after the optical disk 10 is inserted into the optical disk drive.

First, the optical pickup 14 is moved to a mirror portion on the inner periphery of the optical disk 10 (step S1), and a push-pull signal voltage (Vin) at that position (xin) is read (step S2). As a method of moving the inner circumference of the optical disc 10 to the mirror section, the track is moved to the innermost track by a normal access operation, and then the tracking servo system is turned off. It is realized by pressing against. A method of applying a DC voltage to the actuator unit 42 in the optical pickup 14 and moving the objective lens 41 to the inner mirror unit can also be used.

Next, the optical pickup 14 is moved to the optical disk 1.
0 (step S3) and the position (xou)
The push-pull signal voltage (Vout) at t) is read (step S4). The method of moving to the outer mirror unit is the same as the method of moving to the inner mirror unit.
At the position of the outer mirror portion, the tilt actuator 1 is adjusted so that the push-pull signal voltage Vout becomes the same value as the push-pull signal voltage Vin (step S5).
5 is tilt-corrected by the correction angle (θout) (step S6). That is, the optical pickup 14 is set to have the same inclination as that of the case with respect to the inner circumference of the optical disc 10.

The cause of the tilt of the optical disk 10 is mainly due to the weight of the optical disk 10, and therefore, it can be considered that there is almost no tilt at the inner circumference. By performing the above-described tilt correction, the tilt at the outer circumference is obtained. Can be corrected to the same level as the inner circumference.

When an arbitrary position on the optical disk 10 is accessed, a function f (x, θ) is obtained from the position x of the optical disk 10 and the inclination correction angle θout at the outer periphery of the optical disk.
out), the angle can be corrected by obtaining the correction angle (step S7).

As the tilt actuator 15, it is necessary to change the tilt angle in proportion to the input signal, and a DC servo motor or a pulse motor is used.
When a pulse motor is used, it is necessary to drive the pulse motor after converting the output of the arithmetic processing equipment 5 into a pulse train without performing D / A conversion.

FIG. 5 shows a mirror on the outer circumference of the optical disk 10 when the distance r from the center of the optical disk 10 is taken on the horizontal axis and the amount of tilt correction in the mirror on the inner circumference of the optical disk 10 is set to zero (reference value). 7 is a graph of the amount of tilt correction in the section. A portion connected by a dotted line indicates a user area having a track groove. Since a tracking error signal is mixed therein, tilt correction cannot be performed. Therefore, the portion is approximately obtained using a polynomial function such as the following equation (1). .

Since the main cause of the tilt generated in the optical disk 10 is caused by its own weight, the relationship between the scanning position of the light spot on the optical disk 10 and the tilt can be approximated by a function based on the material dynamics. For example, in a state in which a plate-like rectangular member having a thickness is supported in a cantilever manner for the purpose of horizontal holding, bending due to its own weight occurs. In this case, the position from the tip is x, and the position x
, The total length l, the second moment of area I, the Young's modulus E, and the weight w per unit length,
The slope i (x) is represented by the following equation 1.

[0038]

(Equation 1)

Therefore, by substituting the tilt correction value and the outer mirror position at which the value of the DC push-pull signal at the outer mirror section becomes equal to the value at the inner mirror section into this function, the individual optical discs 10 Weight w and cross section 2 that vary every time
The quotient (w / I) with the next moment I is obtained.

By substituting the information on the scanning position of the optical disk 10 into the equation (1) containing this coefficient, the amount of tilt at the scanning position can be calculated and corrected by the tilt actuator 15. .

It is necessary to model the actual optical disk 10 with a disk receiving a vertical load symmetrical with respect to the center. In this case, the inclination can be corrected in the same manner as described above.

According to the present invention described above, the following configuration can be added. (1) Focus error detecting optical system and focus servo means for focusing a light spot on a recording surface of an optical disc, and tracking error detecting optical system and tracking servo means for following a light spot on an information track in the optical disc An optical disk drive having means for mechanically or optically correcting the relative attitude angle between the objective lens and the optical disk, and correcting the effect of the tilt of the light spot formed on the optical disk surface apparatus.

(2) In the optical disk drive described in Appendix 1, the objective lens and the objective lens are adjusted so that the DC offset of the push-pull signal at the mirror on the outer circumference of the optical disk is equivalent to the value at the mirror on the inner circumference of the optical disk. Means for mechanically or optically correcting the relative attitude angle between the optical discs, and calculating the angle correction amount for each optical disc position accessed in the user area where the track groove exists, based on the correction amount at the outer circumference of the optical disc; An optical disk drive device, comprising: means for correcting, for correcting a relative attitude angle between an objective lens and an optical disk.

That is, the DC offset amount of the push-pull signal, which is a kind of tracking error signal, is measured in the area (mirror section) where there is no track groove in each of the inner circumference of the optical disk and the outer circumference of the optical disk. The relative attitude angle between the objective lens and the optical disk is mechanically or optically adjusted so that the DC offset amount of the push-pull signal at the mirror unit of the optical disk becomes equivalent to the value of the DC offset amount at the inner mirror unit of the optical disk. Correction.

Further, based on the correction amount at the outer peripheral portion of the optical disk, an angle correction amount is obtained based on a predetermined function for each optical disk position accessed in the user area where the track groove exists, and the angle is corrected.

As a result, the relative attitude angle between the objective lens and the optical disk is corrected, and the influence of the inclination of the light spot formed on the optical disk surface is corrected.

[0047]

According to the present invention, there is no need to use a dedicated angle detector and no need to construct a special optical system.
It is possible to provide an optical disk drive device that can adjust the relative attitude angle between the objective lens and the outer circumference of the optical disk in the optical pickup, and correct the adverse effect during the light spot scanning due to the inclination of the outer circumference of the optical disk.

Further, according to the present invention, the relative position between the objective lens in the optical pickup and an arbitrary position on the optical disk can be reduced without using a dedicated angle detector and without having to configure a special optical system. It is possible to provide an optical disk drive device capable of adjusting the attitude angle and correcting an adverse effect at the time of light spot scanning due to the inclination of an arbitrary position on the optical disk.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical disk drive according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of an optical pickup and a tilt actuator according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a control system of the optical disk drive according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a tilt correction process in the optical disc drive according to the embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the distance from the center of the optical disk and the amount of tilt correction in the optical disk drive according to the embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a conventional optical disk drive.

FIG. 7 is a diagram showing a tilt servo system in a conventional optical disk drive.

FIG. 8 is a schematic configuration diagram of another example of the conventional optical disk drive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2-piece PD 2 Differential amplifier 3 Low-pass filter 4 A / D converter 5 Arithmetic processing unit 6 D / A converter 7 Driver 10 Optical disk 11 Spindle motor 12 Turntable 13 Optical disk clamper 14 Optical pickup 15 Tilt actuator 41 Objective lens 42 Actuator section 43 Pickup body 44 Carriage 45 Rotation axis 46 Servo motor 47 Screw screw 48 Bearing 49 Guide rail

Claims (3)

[Claims] 1. An optical disk drive device for performing information recording by scanning a track groove on an information recording surface of an optical disk with an optical spot through an objective lens in an optical pickup, wherein each of an inner circumference of the optical disk and an outer circumference of the optical disk. In an area where there is no track groove, the offset amount detecting means for detecting the offset amount of the push-pull signal which is a kind of tracking error signal, and the offset amounts on the inner circumference and the outer circumference of the optical disk detected by the offset amount detecting means are equal. And an angle adjusting means for adjusting a relative attitude angle of the objective lens in the optical pickup with respect to the information recording surface of the optical disk. 2. An optical disk drive device for performing information scanning by scanning a track groove on an information recording surface of an optical disk with an optical spot via an objective lens in an optical pickup, wherein each of an inner circumference of the optical disk and an outer circumference of the optical disk. An offset amount detecting means for detecting an offset amount of a push-pull signal, which is a kind of tracking error signal, in an area having no track groove; and an optical disk based on the inner and outer offset amounts of the optical disk detected by the offset amount detecting means. Calculating means for obtaining a tilt amount with respect to the inner circumference of the outer circumference of the optical disk, and obtaining a tilt correction amount for each optical disc position scanned by the light spot in a region where the track groove exists, based on the obtained tilt amount; The optical disk scanned according to the obtained tilt correction amount An angle adjusting means for adjusting the relative attitude angle of the objective lens in the optical pickup with respect to the information recording surface of the optical disk for each optical disc position. 3. The offset amount detecting means includes: a two-segment photodetector divided in a radial direction of reflected light from the optical disc; and a push-pull based only on a tilt of the optical disc based on a detection signal of the two-segment photodetector. 3. The optical disk drive according to claim 1, further comprising a differential amplifier for obtaining a signal.