JP3340281B2 - Disk unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device, and more particularly to a disk device using an optical disk on which information such as music and data is recorded, such as a compact disk and a mini disk.

[0002]

2. Description of the Related Art Conventionally, in a disk drive, a tracking servo is closed in order to grasp an eccentricity caused by a displacement between a center of rotation and a center of the disk due to mounting of a disk or mounting of a mounting table, and offset of a head. While the head is following the track of the eccentric disk, the low-frequency component of the output of the tracking servo is extracted, and the information is multiplied by the voltage-displacement sensitivity of the head driving means and the head transport means to determine the amount of eccentricity. It was calculated and learned.

In the design of a tracking servo for a disk drive, a tracking gain is set so that a sufficient data reading margin is obtained by the tracking servo even for the maximum eccentricity conceivable from the standard value of the disk and the mechanical crossing of the disk drive. It was designed in consideration of.

[0004]

However, when vibration in the tracking direction is applied to the device during learning of eccentricity,
The tracking servo prevents the head from being separated from the track where data is recorded due to the vibration,
A driving command voltage is output to the head driving means so as to cancel the vibration acceleration. Therefore, when the low-frequency component of the output voltage of the tracking servo is extracted, a component for vibration is added to a component for eccentricity, so that there is a problem that the actual eccentric amount of the device cannot be correctly grasped.

In the design of the tracking servo in consideration of the maximum eccentricity of the disk drive, it is necessary to increase the servo gain in the disk rotation frequency band. However, the former method makes it difficult to secure a tracking phase margin, and the tracking servo system becomes unstable even when a disk with small eccentricity is mounted. . The latter means is sensitive to the influence of high-frequency disturbances such as scratches on the disk, and also has the problem that the tracking servo becomes unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a disk drive capable of accurately detecting the eccentricity of a mounted disk even under vibration.

[0007]

According to a first aspect of the present invention, there is provided a disk drive, comprising: a drive unit for rotating a disk on which music information and data are recorded; and information recorded on a circumferential or spiral track of the disk. A head for reading, a head transport means for displacing the head in the track direction, a tracking error signal generating means for generating a tracking error signal based on a read signal from the head, and a head for working to reduce the tracking error signal. Tracking servo means for generating a drive instruction signal for position control on a track on which is recorded, a head drive means for driving a head transport means by a drive instruction signal from the tracking servo means, and An acceleration detector for detecting radial acceleration, and the acceleration Acceleration voltage adjustment means for adjusting the output from the output device; and subtraction means for subtracting the low-frequency component of the acceleration voltage signal of the acceleration voltage adjustment means from the low-frequency component of the drive instruction signal output by the tracking servo means. The amplification degree of the adjusting means is determined by the drive command voltage output by the tracking servo means and the acceleration voltage generated when the specified acceleration is applied to the apparatus as external vibration in order to generate a specified acceleration by the head transport means. The eccentricity of the loaded disc is determined from the result from the subtracting means while the tracking servo is closed, with the setting being made equal.

[0008]

According to the first aspect of the present invention, when the tracking servo is closed, the acceleration voltage from the acceleration detector is subtracted from the tracking servo drive command voltage, so that the current eccentricity can be accurately obtained even under vibration. It becomes possible to grasp.

For example, with the tracking servo closed, the result (Vs [V]) from the subtracting means is measured, and the voltage-displacement sensitivity (Gd) of the head conveying means is measured from the head driving means.
[M / V]), the current eccentricity H [m] is derived from (Equation 1).

H = Vs · Gd [m] (Equation 1)

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an embodiment of a disk drive according to the present invention .

This optical disk device includes an optical disk 1, a spindle motor 2, an objective lens 3, an optical pickup 4,
Acceleration sensor 5, tracking error amplifier 6, tracking servo circuit 7, tracking driver 8, acceleration voltage amplifying circuit 9, low-pass filter (LPF) 10, 1
1, a CPU 12, and a gain switching circuit 14 for tracking servo.

Information such as music is recorded on a circumferential or spiral track of the optical disc 1, and the optical disc 1 is driven to rotate by a spindle motor 2. On the optical disc 1, a light beam of a laser beam emitted from a light source (not shown) is
The light is irradiated in a converged state through the.

The objective lens 3 is supported and driven on the optical pickup 4 by a tracking actuator (not shown), and can be moved in the radial direction of the disk by a current flowing through the actuator.

The optical pickup 4 has a photoelectric conversion element for receiving the reflected light from the optical disk 1 and generating an electric signal corresponding to the received optical signal, and outputs an output signal of the photoelectric conversion element to the tracking error amplifier 6. Is done.

The tracking error amplifier 6 generates a tracking error signal which is a position signal of a track on which data on the optical disc 1 is recorded, and outputs the signal to the tracking servo circuit 7.

The tracking servo circuit 7 includes a phase compensation circuit and a gain compensation circuit for performing tracking servo for controlling the position of the objective lens 3 so that the focal point of the laser beam from the optical pickup 4 is irradiated onto the track of the optical disk 1. It is composed of The drive instruction voltage a of the output voltage of the tracking servo circuit 7 enters the tracking driver 8 via the gain switching circuit 14 for switching the tracking servo loop gain, is converted into a current by the tracking driver 8, and is supplied to the tracking actuator to be supplied to the objective lens. 3 is driven.

The output signal of the tracking servo circuit 7 is input to the CPU 12 through the LPF 10 and
The voltage is digitally converted by the A / D converter 2 and the voltage can be observed in real time.

The acceleration sensor 5 is fixed on the optical pickup 4 or on the same rigid body as the optical pickup 4, and detects the radial acceleration of the disk. The output of the acceleration sensor 5 is amplified by the acceleration voltage
1 from the A / D converter of the CPU 12.
The acceleration voltage amplifying circuit 9 applies the acceleration Ar to the objective lens 3 via the gain switching circuit 14, the tracking driver 8, and the tracking actuator when a certain voltage Vr is output from the output voltage a of the tracking servo circuit. It is set to amplify the voltage of the acceleration sensor 5 so that the acceleration voltage b becomes Vr when the acceleration Ar comes in from the outside.

The drive instruction signal a and the acceleration voltage b of the tracking servo measured by the A / D converter of the CPU 12
The voltage passed through the LPFs 10 and 11 is subtracted by a subtractor 13 in the CPU. When the result is Vs [V], the eccentricity H [m] of the disk mounted on the device under vibration is
It can be obtained by (Equation 2) .

H = Vs · G1 / G2 / G3 [m] (Equation 2) G1: Voltage-voltage conversion gain [V of the gain switching circuit 14
/ V] G2: Voltage-current conversion gain [I / V] of tracking driver 8 G3: Current-displacement conversion gain [m / I] of tracking actuator The gain switching circuit 14 of the tracking servo is a CPU 1
2, the gain can be switched. In a normal state, the gain is reduced in a state where the switch shown in the figure is turned on . However, as shown in FIGS.
Only when the current absolute value of the eccentricity H obtained by (Equation 2) exceeds a certain comparator level, the CPU 12 is controlled to turn off the switch and increase the tracking gain.

[0022]

According to the disk device according to the claims as described above, according to the present invention, to remove the influence of vibration in the training of the eccentric always possible to grasp the accurate eccentricity amount, mounting a large deal of eccentric disc In this state, the data recorded on the disk can be read stably.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram for a tracking servo in a first embodiment .
FIG. 5 is an explanatory diagram of the operation of the gain switching circuit.

[Explanation of symbols]

 Reference Signs List 1 optical disk 2 spindle motor 3 objective lens 4 optical pickup 5 acceleration sensor 6 tracking error amplifier 7 tracking servo circuit 8 tracking driver 9 acceleration voltage amplifying circuit 10 low-pass filter (LPF) 11 low-pass filter (LPF) 12 CPU 13 CPU Subtractor 14 Gain switching circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-39143 (JP, A) JP-A-4-285729 (JP, A) JP-A-6-52563 (JP, A) JP-A-7- 29196 (JP, A) JP-A-5-109179 (JP, A) JP-A-62-279527 (JP, A) JP-A-63-225974 (JP, A) JP-A-5-159330 (JP, A) JP-A-9-231594 (JP, A) JP-A-8-329483 (JP, A) JP-A-2-76369 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/09-7/095

Claims (1)

(57) [Claims] A drive unit for rotating a disk on which music information or data is recorded, a head for reading information recorded on a circumferential or spiral track of the disk,
Head transport means for displacing the head in the track direction,
Tracking error signal generating means for generating a tracking error signal based on a read signal from the head;
A tracking servo means for generating a drive instruction signal for controlling the position of the head on the track on which data is recorded on the disk, and a head drive means driven by the drive instruction signal from the tracking servo means. Head driving means, an acceleration detector for detecting radial acceleration of the disk acting on the head, an acceleration voltage adjusting means for adjusting an output from the acceleration detector, and a driving instruction output from the tracking servo means. Subtracting means for subtracting the low-frequency component of the acceleration voltage signal from the low-frequency component of the signal from the low-frequency component of the signal. The drive instruction voltage output from the servo means and the specified acceleration are used as external vibrations in the device. Added was set so that the acceleration voltage generated equals case, the disk device configured to grasp the amount of eccentricity of the disk mounted from the result from the subtraction means with closed tracking servo.