JP2000215469A - Optical disk drive - Google Patents

Abstract

(57) [Summary] To realize a one-track jump in consideration of a reduction in sensitivity of a tracking coil caused by movement of an objective lens. SOLUTION: A displacement of an objective lens 3 is detected by a position sensor 5 and is input to a torque gain generating section 15. The torque gain generation unit 15 generates a torque gain for correcting a decrease in drive sensitivity of the tracking coil 6 with respect to the displacement of the objective lens 3. The output is multiplied by a kick torque signal or a brake torque signal from the kick / brake torque generator 13 by the multiplier 14 to generate a kick torque signal or a brake torque signal corrected for the sensitivity drop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive, and more particularly, to an optical disk drive for controlling a one-track jump for moving a light beam to an adjacent track.

[0002]

2. Description of the Related Art In an optical disk recording / reproducing apparatus for recording / reproducing data on / from an optical disk, a data track is made to follow a light beam emitted from an optical pickup by a tracking servo to appropriately access a desired track. I can do it.

Here, one-track jump control is required to move a light beam to an adjacent track. As this control method, a control method called so-called bang-bang control is generally used. As shown in FIG. 2, the bang-bang control is performed by applying a pulse-type drive signal having a fixed time width Tb and a fixed voltage level Vb, which have opposite polarities in kick and brake, to the tracking coil.

However, the bang-bang control can move at the fastest speed in an ideal optical pickup and can simplify the control system, but it is a so-called open control, and has a problem in stability when there is a disturbance. Further, in the objective lens of the shaft sliding type optical pickup, the sensitivity of the tracking coil may be reduced during the jump, the jump moving distance changes, and an error occurs at the position immediately after the jump. Since the error needs to be converged by the tracking servo, the time required for establishing the tracking error immediately after the jump becomes longer, and the time required for the track jump becomes longer.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the time required for a tracking pull-in servo immediately after a jump by realizing a one-track jump in consideration of a decrease in the sensitivity of a tracking coil caused by movement of an objective lens. As an issue.

[0006]

According to a first aspect of the present invention, there is provided an optical disc driving apparatus for driving an objective lens from a state in which a light beam follows a track of an optical disc to a track adjacent to the track by driving an objective lens. An optical disk drive for jumping the light beam, comprising: a drive unit for driving an objective lens; a position sensor for detecting displacement of the objective lens; a signal generation unit for generating a kick torque signal and a brake torque signal; A drive sensitivity correction unit that corrects the drive sensitivity of the drive unit based on the displacement of the objective lens that detects the output of the unit by the position sensor, and supplies the output to the drive unit.

According to a second aspect of the present invention, in the optical disk driving device, the driving unit is a tracking coil.

According to a third aspect of the present invention, the drive sensitivity correction is a correction that is a reverse characteristic of the drive sensitivity characteristic of the drive unit with respect to the displacement of the objective lens.

According to a fourth aspect of the present invention, in the optical disk drive device, the drive sensitivity correction section multiplies the correction data storage section holding the drive sensitivity correction data by an output signal of the signal generation section and an output of the correction data storage section. And a part.

According to a fifth aspect of the present invention, in the optical disk drive device, the correction data storage section holds the inverse characteristic of the drive sensitivity characteristic of the drive section with respect to the displacement of the objective lens as data obtained by approximating a broken line.

According to a sixth aspect of the present invention, there is provided an optical disk drive apparatus for driving an objective lens from a state in which a light beam follows a track of an optical disk to jump an optical beam to an adjacent track. , A position sensor that detects the displacement of the objective lens, a signal generation unit that generates a kick torque signal and a brake torque signal, and an output of the signal generation unit.
A drive sensitivity correction unit that corrects the drive sensitivity of the drive unit based on the displacement of the objective lens detected by the position sensor, and a light receiving unit that generates a tracking error signal from the return light of the light beam,
A reference buffer that holds the data of the standard tracking error signal during the jump and outputs a standard tracking error signal based on the time information from the start of the jump, and the difference between the tracking error signal and the standard tracking error signal , And an addition unit that adds the output of the drive sensitivity correction unit and the output of the comparison unit and supplies the output to the drive unit.

The operation of the above means will be described. The drive unit such as a tracking coil for driving the objective lens has lower drive sensitivity as the objective lens is displaced from the center position. This reduction in drive sensitivity is corrected by a drive sensitivity correction unit.
The position sensor detects the displacement of the objective lens from the center position, and based on the displacement, corrects the output of the signal generation unit with the drive sensitivity correction unit, thereby driving the objective lens with the corrected torque. A one-track jump independent of the displacement of the objective lens is realized.

In addition, by making the drive sensitivity correction reverse to the drive sensitivity characteristic of the drive unit with respect to the displacement of the objective lens, the correction can be performed with high accuracy.

Further, the drive sensitivity correction section includes a correction data storage section holding data of drive sensitivity correction, and a multiplication section for multiplying an output signal of the signal generation section and an output of the correction data storage section. This can be realized with a simple configuration.

Further, the data held in the correction data storage section is data obtained by approximating the inverse characteristic of the drive sensitivity characteristic of the drive section with respect to the displacement of the objective lens by a polygonal line, so that the storage capacity required for the correction data storage section is obtained. Can be greatly reduced.

Further, the difference between the tracking error signal and the standard tracking error signal is obtained, and a signal obtained by adding the output of the drive sensitivity correction section and the signal of the difference is supplied to the drive section. The effect of the feedback loop is added to the effect of correcting the sensitivity, and a more accurate one-track jump can be realized.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described.
This will be described with reference to FIGS. First, the control block configuration of the one-track jump servo of the optical disk drive of the present embodiment will be described with reference to FIG.

The optical pickup 1 includes a laser 2, an objective lens 3, a light receiving element 4, a position sensor 5 for detecting a displacement of the objective lens 3, and a tracking coil 6 for driving the objective lens 3. The reflected light of the light beam emitted from the laser 2 to the optical disk 7 through the objective lens 3 is received by the light receiving element 4 and a tracking error signal (hereinafter, referred to as a “TE signal”) is generated.

The A / D converter 8 converts the TE signal into a digital signal. The digitized TE signal is compared with a reference signal from a reference buffer 10 in a comparator 9. The reference buffer 10 stores a standard TE signal level per unit time when a one-track jump is performed. Reference buffer 10
Is the time information T since the start of the one-track jump
j, and outputs a standard TE signal level at that time as a reference signal.

Therefore, the output of the comparing section 9 for comparing the actual TE signal with the reference signal has the meaning of a one-track jump error signal. The output of the comparison unit 9 is
The gain is multiplied by 1 and the phase is compensated by the phase compensator 12.

On the other hand, a kick torque and a brake torque necessary for a track jump are generated by a kick / brake torque generator 13. Kick / brake torque generator 13
Is the time information T since the start of the one-track jump
j, and outputs a signal for generating kick torque and brake torque. This output signal is, for example, a signal similar to the conventional bang-bang control drive signal shown in FIG.
It is not limited to this.

The output signal from the kick / brake torque generator 13 is multiplied by a torque gain from a torque gain generator 15 by a multiplier 14. Torque gain generator 15
Inputs a signal from a position sensor 5 that detects a radial displacement of the objective lens 3 on the optical disk 7 and outputs a torque gain corresponding to the displacement of the objective lens 3. Details of this part will be described later.

The output of the multiplier 14 is added to the output of the phase compensator 12 by the adder 16, and the result is added to the D / A converter 17
Is converted to an analog signal and supplied to the tracking coil 6. The tracking coil 6 drives the objective lens 3 so that the light beam moves to an adjacent track on the optical disc 7. The optical disk 7 is rotated by a spindle motor 18.

As described above, the driving torque required for kicking or braking is supplied from the multiplier 14, and the feedback signal required for feedback control for reducing the jump error is supplied from the phase compensator 12.

Next, the torque gain generator 15 will be described in detail. The drive sensitivity in the tracking direction depends on the objective lens 3
Decrease as the displacement from the center of the lens increases. FIG.
9 shows an example of the relationship between the displacement of the objective lens and the reduction in the drive sensitivity in the tracking direction.

FIG. 3 shows that the sensitivity when the displacement of the objective lens 3 is 0 is 0.39, whereas the sensitivity when the displacement of the objective lens 3 is +0.2 mm or -0.2 mm is 0. 35, it can be seen that the sensitivity is reduced to 0.24 when the displacement of the objective lens 3 is +0.4 mm or -0.4 mm, and the drive sensitivity is reduced as the displacement increases.

In order to correct such a reduction in drive sensitivity,
The torque gain generator 15 holds a torque gain as shown in FIG. FIG. 4 is obtained by dividing the drive sensitivity when the objective lens 3 is at the center position by the drive sensitivity according to the displacement of the position of the objective lens 3.
For example, when the objective lens 3 is displaced by ± 0.2 mm, the drive sensitivity is reduced by about 10% in FIG.

The torque gain generating section 15 is provided, for example, in FIG.
Are stored in a memory in the form of a table, and the torque gain is obtained by indexing the table with the displacement of the objective lens 3 from the position sensor 5. In this case, a memory capacity corresponding to the quantization unit of the displacement of the objective lens 3 is required.

Therefore, in order to reduce the memory to be used, the relationship between the displacement of the objective lens 3 and the output torque gain shown in FIG. 4 is made a polygonal line as shown in FIG. The table has the torque gain when the displacement of the objective lens 3 is ± 0.1 mm and ± 0.2 mm, and performs a polygonal line approximation. In this way, the used capacity of the memory can be significantly reduced without lowering the accuracy.

In FIG. 5, the displacement of the objective lens 3 is ±
Although it is shown up to 0.2 mm, the torque gain up to the position where it is further displaced can be changed as necessary.
5 may be provided.

The torque gain generator 15 and the multiplier 14 configured as described above function as a drive sensitivity corrector. The kick / brake torque generating unit 13 multiplies the kick torque signal or the brake torque signal from the kick / brake torque generating unit 13 by using the torque gain generated by the torque gain generating unit 15.
, The output signal from the multiplier 14 is
It becomes a kick torque signal or a brake torque signal whose drive sensitivity has been corrected.

By driving the tracking coil 6 with the kick torque signal or the brake torque signal whose drive sensitivity has been corrected, a one-track jump independent of the displacement of the objective lens 3 is realized.

It is to be noted that although the above-described effect is obtained only by outputting to the tracking coil only by the output signal from the multiplying unit 14, a more accurate one-track jump can be realized by combining the above-described feedback control. It becomes possible.

[0034]

According to the optical disk drive of the present invention,
Since the sensitivity decrease due to the movement of the objective lens from the center during the one-track jump is corrected, the influence of the displacement of the objective lens on the one-track jump is reduced.
In particular, even when the objective lens is largely moving from the center, such as when the thread servo is not catching up immediately after a track jump of several hundred tracks, the jump distance does not change.

Further, disturbance to the feedback control during the one-track jump is reduced, and the stability and accuracy of the one-track jump are further improved. Further, the time required for the tracking pull-in servo immediately after the one-track jump is reduced, and the seek speed of the optical disk drive system is improved.

Further, by combining the feedback control, it is possible to realize a more accurate one-track jump.

[Brief description of the drawings]

FIG. 1 is a diagram showing a control block configuration of a one-track jump servo of an optical disk drive according to an embodiment of the present invention.

FIG. 2 is a diagram showing drive signals for bang-bang control.

FIG. 3 is a diagram illustrating an example of a relationship between a displacement of an objective lens and a reduction in drive sensitivity in a tracking direction.

FIG. 4 is a diagram illustrating a torque gain held by a torque gain generation unit.

FIG. 5 is a diagram illustrating a case where the torque gain held by the torque gain generation unit is a polygonal line.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical pickup, 2 ... Laser, 3 ... Objective lens, 4
.., Light receiving element, 5, position sensor, 6, tracking coil, 7, optical disk, 8, A / D converter, 9, comparison unit,
DESCRIPTION OF SYMBOLS 10 ... Reference buffer, 11 ... Amplification part, 12 ... Phase compensation part, 13 ... Kick / brake torque generation part, 14
... multiplier, 15 ... torque gain generator, 16 ... adder,
17: D / A converter, 18: spindle motor, S1 ...
TE signal, Tj: time information after starting one track jump

Claims (6)

[Claims] 1. An optical disk drive for jumping the light beam to an adjacent track by driving an objective lens from a state in which the light beam follows a track of the optical disk, comprising: a drive unit for driving the objective lens; A position sensor that detects displacement of the objective lens, a signal generation unit that generates a kick torque signal and a brake torque signal, and an output of the signal generation unit, based on the displacement of the objective lens that is detected by the position sensor. An optical disk drive device comprising: a drive sensitivity correction unit that corrects drive sensitivity of a drive unit and supplies an output to the drive unit. 2. The optical disk drive according to claim 1, wherein the driving unit is a tracking coil. 3. The optical disk drive device according to claim 1, wherein the drive sensitivity correction is a correction that is a reverse characteristic of a drive sensitivity characteristic of the drive unit with respect to a displacement of the objective lens. 4. The drive sensitivity correction unit includes: a correction data storage unit that holds the drive sensitivity correction data; and a multiplication unit that multiplies an output signal of the signal generation unit and an output of the correction data storage unit. The optical disk drive according to claim 1, further comprising: 5. The optical disk according to claim 4, wherein the correction data storage unit holds the inverse characteristic of the drive sensitivity characteristic of the drive unit with respect to the displacement of the objective lens as data obtained by approximating a polygonal line. Drive. 6. An optical disk drive for jumping the light beam to an adjacent track by driving an objective lens from a state where the light beam follows a track of the optical disk, comprising: a driving unit for driving the objective lens; A position sensor that detects displacement of the objective lens, a signal generation unit that generates a kick torque signal and a brake torque signal, and an output of the signal generation unit, based on the displacement of the objective lens that is detected by the position sensor. A drive sensitivity correction unit for correcting the drive sensitivity of the drive unit, a light receiving unit for generating a tracking error signal from the return light of the light beam, and holding data of a standard tracking error signal during the jump, from the start of the jump. A reference bar that outputs the standard tracking error signal based on the time information of A comparison unit that calculates a difference between the tracking error signal and the standard tracking error signal; an output of the drive sensitivity correction unit and an output of the comparison unit; and an output is supplied to the drive unit. An optical disk drive comprising an adder.